From 9d0828b9ec39308b3eaaf40204cc827e06563518 Mon Sep 17 00:00:00 2001
From: Wiebren Braakman <info@wiebren.nl>
Date: Fri, 25 Sep 2026 05:15:55 +0200
Subject: [PATCH] [ruby] fix: build_from_hash drops every attribute inherited
 from an allOf parent (#24892)

* [ruby] fix: build_from_hash maps attributes inherited from allOf parents

A discriminator allOf child generates as a real subclass, but
build_from_hash iterated only openapi_types/attribute_map - class methods
that dispatch on the child class in every frame of the ancestry, so a
parent's attributes were never mapped from the wire hash: a required
inherited attribute made deserialization raise ArgumentError, an optional
one came back silently nil. The pre-existing super(attributes) call could
not help: its result was discarded, and it iterated the child's own types
anyway.

Walk the ancestry merging each ancestor's openapi_types and attribute_map
(the child wins on a name clash) and drop the discarded-result super
call. RubyClientCodegenTest asserts the walk on the generated two-level
Lizard < Reptile < Pet fixture (fails without the template change), and
the three petstore custom base_object specs now deserialize a Cat that
carries its parent's attributes.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GcwZ1arjLZNpetHz2a3TJz

* update ruby samples

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GcwZ1arjLZNpetHz2a3TJz

* [ruby] fix: to_hash loses the same inherited attributes

The serialization direction has the identical defect: attribute_map and
openapi_nullable dispatch on the child class in every ancestor frame, so
the inherited super chain only repeated the child's own attributes and a
round-tripped allOf child lost its parent's fields again on the way out.
Walk the ancestry the same way build_from_hash now does; for a model
without a generated parent the walk does not run and the output is
unchanged.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GcwZ1arjLZNpetHz2a3TJz

* update ruby samples

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GcwZ1arjLZNpetHz2a3TJz

* [ruby] fix: ancestor nullability defers to a child's redeclaration, and Set loads

Two findings from review: the merged-nullable union let a parent's
nullable flag survive a child redeclaring the attribute as non-nullable -
an ancestor's entry now only applies to attributes no nearer class
declares - and the walk evaluates openapi_nullable eagerly for every
to_hash call, so the generated models require 'set' explicitly instead of
leaning on the Set builtin autoload rubies before 3.2 do not have.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GcwZ1arjLZNpetHz2a3TJz

* [ruby] fix: only hand an initializer the attributes it accepts, and load Set only where used

build_from_hash and to_hash now take their attribute map from
acceptable_attribute_map, the same map the generated initializer
validates against. For a generated allOf child it is identical to the
ancestry walk; for a consumer subclass that narrows attribute_map it
keeps the attributes to the ones the subclass accepts, as on master,
instead of passing its parent's fields to an initializer that rejects
them. The ancestry walk remains for openapi_types and openapi_nullable.

require 'set' is emitted only for generic models, the only ones whose
openapi_nullable uses Set; enum classes and oneOf/anyOf modules no
longer carry it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

* [ruby] refactor: merge inherited types and nullability with the acceptable_attribute_map idiom

acceptable_openapi_types and acceptable_openapi_nullable merge along the
allOf ancestry the way acceptable_attribute_map already does, so
build_from_hash and to_hash lose their while loops and the require 'set'
block. Also drops the redundant map.key? guard, shortens the generated
comments and specs, and reverts the stray ruby-faraday Gemfile.lock bump.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

* [ruby] fix: models whose superclass is not a generated model do not delegate to it

An alias to an array (ArrayAlias < Array) has a parent, so the ancestry
helpers and the initializer called superclass methods Array does not
provide. Gate the delegation on parentModel, so every model has a base case.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
---
 .../ruby-client/base_object.mustache          | 24 ++++----
 .../partial_model_generic.mustache            | 36 ++++++++---
 .../codegen/ruby/RubyClientCodegenTest.java   | 59 +++++++++++++++++++
 .../lib/openapi_client/models/bird.rb         | 29 ++++++---
 .../lib/openapi_client/models/category.rb     | 29 ++++++---
 .../lib/openapi_client/models/data_query.rb   | 32 ++++++----
 .../openapi_client/models/default_value.rb    | 29 ++++++---
 .../models/number_properties_only.rb          | 29 ++++++---
 .../lib/openapi_client/models/pet.rb          | 29 ++++++---
 .../lib/openapi_client/models/query.rb        | 29 ++++++---
 .../lib/openapi_client/models/tag.rb          | 29 ++++++---
 ...st_form_object_multipart_request_marker.rb | 29 ++++++---
 ...ue_object_all_of_query_object_parameter.rb | 29 ++++++---
 ...rue_array_string_query_object_parameter.rb | 29 ++++++---
 .../lib/openapi_client/models/bird.rb         | 29 ++++++---
 .../lib/openapi_client/models/category.rb     | 29 ++++++---
 .../lib/openapi_client/models/data_query.rb   | 32 ++++++----
 .../openapi_client/models/default_value.rb    | 29 ++++++---
 .../models/number_properties_only.rb          | 29 ++++++---
 .../lib/openapi_client/models/pet.rb          | 29 ++++++---
 .../lib/openapi_client/models/query.rb        | 29 ++++++---
 .../lib/openapi_client/models/tag.rb          | 29 ++++++---
 ...st_form_object_multipart_request_marker.rb | 29 ++++++---
 ...ue_object_all_of_query_object_parameter.rb | 29 ++++++---
 ...rue_array_string_query_object_parameter.rb | 29 ++++++---
 .../lib/openapi_client/models/bird.rb         | 29 ++++++---
 .../lib/openapi_client/models/category.rb     | 29 ++++++---
 .../lib/openapi_client/models/data_query.rb   | 32 ++++++----
 .../openapi_client/models/default_value.rb    | 29 ++++++---
 .../models/number_properties_only.rb          | 29 ++++++---
 .../lib/openapi_client/models/pet.rb          | 29 ++++++---
 .../lib/openapi_client/models/query.rb        | 29 ++++++---
 .../lib/openapi_client/models/tag.rb          | 29 ++++++---
 ...st_form_object_multipart_request_marker.rb | 29 ++++++---
 ...ue_object_all_of_query_object_parameter.rb | 29 ++++++---
 ...rue_array_string_query_object_parameter.rb | 29 ++++++---
 .../models/additional_properties_class.rb     | 29 ++++++---
 .../petstore/models/all_of_with_single_ref.rb | 29 ++++++---
 .../lib/petstore/models/animal.rb             | 29 ++++++---
 .../lib/petstore/models/api_response.rb       | 29 ++++++---
 .../models/array_of_array_of_number_only.rb   | 29 ++++++---
 .../petstore/models/array_of_number_only.rb   | 29 ++++++---
 .../lib/petstore/models/array_test.rb         | 29 ++++++---
 .../lib/petstore/models/capitalization.rb     | 29 ++++++---
 .../ruby-autoload/lib/petstore/models/cat.rb  | 32 ++++++----
 .../lib/petstore/models/category.rb           | 29 ++++++---
 .../petstore/models/child_with_nullable.rb    | 32 ++++++----
 .../lib/petstore/models/class_model.rb        | 29 ++++++---
 .../lib/petstore/models/client.rb             | 29 ++++++---
 .../lib/petstore/models/deprecated_object.rb  | 29 ++++++---
 .../ruby-autoload/lib/petstore/models/dog.rb  | 32 ++++++----
 .../lib/petstore/models/enum_arrays.rb        | 29 ++++++---
 .../lib/petstore/models/enum_test.rb          | 29 ++++++---
 .../fake_big_decimal_map200_response.rb       | 29 ++++++---
 .../ruby-autoload/lib/petstore/models/file.rb | 29 ++++++---
 .../petstore/models/file_schema_test_class.rb | 29 ++++++---
 .../ruby-autoload/lib/petstore/models/foo.rb  | 29 ++++++---
 .../models/foo_get_default_response.rb        | 29 ++++++---
 .../lib/petstore/models/format_test.rb        | 29 ++++++---
 .../lib/petstore/models/has_only_read_only.rb | 29 ++++++---
 .../petstore/models/health_check_result.rb    | 29 ++++++---
 .../ruby-autoload/lib/petstore/models/list.rb | 29 ++++++---
 .../lib/petstore/models/map_test.rb           | 29 ++++++---
 ...perties_and_additional_properties_class.rb | 29 ++++++---
 .../lib/petstore/models/model200_response.rb  | 29 ++++++---
 .../lib/petstore/models/model_return.rb       | 29 ++++++---
 .../ruby-autoload/lib/petstore/models/name.rb | 29 ++++++---
 .../lib/petstore/models/nullable_class.rb     | 29 ++++++---
 .../lib/petstore/models/number_only.rb        | 29 ++++++---
 .../models/object_with_deprecated_fields.rb   | 29 ++++++---
 .../lib/petstore/models/order.rb              | 29 ++++++---
 .../lib/petstore/models/outer_composite.rb    | 29 ++++++---
 .../models/outer_object_with_enum_property.rb | 29 ++++++---
 .../petstore/models/parent_with_nullable.rb   | 29 ++++++---
 .../ruby-autoload/lib/petstore/models/pet.rb  | 29 ++++++---
 .../lib/petstore/models/read_only_first.rb    | 29 ++++++---
 .../lib/petstore/models/special_model_name.rb | 29 ++++++---
 .../ruby-autoload/lib/petstore/models/tag.rb  | 29 ++++++---
 ..._freeform_additional_properties_request.rb | 29 ++++++---
 .../ruby-autoload/lib/petstore/models/user.rb | 29 ++++++---
 .../models/additional_properties_class.rb     | 29 ++++++---
 .../petstore/models/all_of_with_single_ref.rb | 29 ++++++---
 .../lib/petstore/models/animal.rb             | 29 ++++++---
 .../lib/petstore/models/api_response.rb       | 29 ++++++---
 .../models/array_of_array_of_number_only.rb   | 29 ++++++---
 .../petstore/models/array_of_number_only.rb   | 29 ++++++---
 .../lib/petstore/models/array_test.rb         | 29 ++++++---
 .../lib/petstore/models/capitalization.rb     | 29 ++++++---
 .../ruby-faraday/lib/petstore/models/cat.rb   | 32 ++++++----
 .../lib/petstore/models/category.rb           | 29 ++++++---
 .../lib/petstore/models/class_model.rb        | 29 ++++++---
 .../lib/petstore/models/client.rb             | 29 ++++++---
 .../lib/petstore/models/deprecated_object.rb  | 29 ++++++---
 .../ruby-faraday/lib/petstore/models/dog.rb   | 32 ++++++----
 .../lib/petstore/models/enum_arrays.rb        | 29 ++++++---
 .../lib/petstore/models/enum_test.rb          | 29 ++++++---
 .../fake_big_decimal_map200_response.rb       | 29 ++++++---
 .../ruby-faraday/lib/petstore/models/file.rb  | 29 ++++++---
 .../petstore/models/file_schema_test_class.rb | 29 ++++++---
 .../ruby-faraday/lib/petstore/models/foo.rb   | 29 ++++++---
 .../models/foo_get_default_response.rb        | 29 ++++++---
 .../lib/petstore/models/format_test.rb        | 29 ++++++---
 .../lib/petstore/models/has_only_read_only.rb | 29 ++++++---
 .../petstore/models/health_check_result.rb    | 29 ++++++---
 .../ruby-faraday/lib/petstore/models/list.rb  | 29 ++++++---
 .../lib/petstore/models/map_test.rb           | 29 ++++++---
 ...perties_and_additional_properties_class.rb | 29 ++++++---
 .../lib/petstore/models/model200_response.rb  | 29 ++++++---
 .../lib/petstore/models/model_return.rb       | 29 ++++++---
 .../ruby-faraday/lib/petstore/models/name.rb  | 29 ++++++---
 .../lib/petstore/models/nullable_class.rb     | 29 ++++++---
 .../lib/petstore/models/number_only.rb        | 29 ++++++---
 .../models/object_with_deprecated_fields.rb   | 29 ++++++---
 .../ruby-faraday/lib/petstore/models/order.rb | 29 ++++++---
 .../lib/petstore/models/outer_composite.rb    | 29 ++++++---
 .../models/outer_object_with_enum_property.rb | 29 ++++++---
 .../ruby-faraday/lib/petstore/models/pet.rb   | 29 ++++++---
 .../petstore/models/property_name_mapping.rb  | 29 ++++++---
 .../lib/petstore/models/read_only_first.rb    | 29 ++++++---
 .../lib/petstore/models/special_model_name.rb | 29 ++++++---
 .../ruby-faraday/lib/petstore/models/tag.rb   | 29 ++++++---
 ..._freeform_additional_properties_request.rb | 29 ++++++---
 .../ruby-faraday/lib/petstore/models/user.rb  | 29 ++++++---
 .../ruby-faraday/lib/petstore/models/whale.rb | 29 ++++++---
 .../ruby-faraday/lib/petstore/models/zebra.rb | 29 ++++++---
 .../spec/custom/base_object_spec.rb           | 30 ++++++++++
 .../models/additional_properties_class.rb     | 29 ++++++---
 .../petstore/models/all_of_with_single_ref.rb | 29 ++++++---
 .../ruby-httpx/lib/petstore/models/animal.rb  | 29 ++++++---
 .../lib/petstore/models/api_response.rb       | 29 ++++++---
 .../models/array_of_array_of_number_only.rb   | 29 ++++++---
 .../petstore/models/array_of_number_only.rb   | 29 ++++++---
 .../lib/petstore/models/array_test.rb         | 29 ++++++---
 .../lib/petstore/models/capitalization.rb     | 29 ++++++---
 .../ruby-httpx/lib/petstore/models/cat.rb     | 32 ++++++----
 .../lib/petstore/models/category.rb           | 29 ++++++---
 .../lib/petstore/models/class_model.rb        | 29 ++++++---
 .../ruby-httpx/lib/petstore/models/client.rb  | 29 ++++++---
 .../lib/petstore/models/deprecated_object.rb  | 29 ++++++---
 .../ruby-httpx/lib/petstore/models/dog.rb     | 32 ++++++----
 .../lib/petstore/models/enum_arrays.rb        | 29 ++++++---
 .../lib/petstore/models/enum_test.rb          | 29 ++++++---
 .../fake_big_decimal_map200_response.rb       | 29 ++++++---
 .../ruby-httpx/lib/petstore/models/file.rb    | 29 ++++++---
 .../petstore/models/file_schema_test_class.rb | 29 ++++++---
 .../ruby-httpx/lib/petstore/models/foo.rb     | 29 ++++++---
 .../models/foo_get_default_response.rb        | 29 ++++++---
 .../lib/petstore/models/format_test.rb        | 29 ++++++---
 .../lib/petstore/models/has_only_read_only.rb | 29 ++++++---
 .../petstore/models/health_check_result.rb    | 29 ++++++---
 .../ruby-httpx/lib/petstore/models/list.rb    | 29 ++++++---
 .../lib/petstore/models/map_test.rb           | 29 ++++++---
 ...perties_and_additional_properties_class.rb | 29 ++++++---
 .../lib/petstore/models/model200_response.rb  | 29 ++++++---
 .../lib/petstore/models/model_return.rb       | 29 ++++++---
 .../ruby-httpx/lib/petstore/models/name.rb    | 29 ++++++---
 .../lib/petstore/models/nullable_class.rb     | 29 ++++++---
 .../lib/petstore/models/number_only.rb        | 29 ++++++---
 .../models/object_with_deprecated_fields.rb   | 29 ++++++---
 .../ruby-httpx/lib/petstore/models/order.rb   | 29 ++++++---
 .../lib/petstore/models/outer_composite.rb    | 29 ++++++---
 .../models/outer_object_with_enum_property.rb | 29 ++++++---
 .../ruby-httpx/lib/petstore/models/pet.rb     | 29 ++++++---
 .../petstore/models/property_name_mapping.rb  | 29 ++++++---
 .../lib/petstore/models/read_only_first.rb    | 29 ++++++---
 .../lib/petstore/models/special_model_name.rb | 29 ++++++---
 .../ruby-httpx/lib/petstore/models/tag.rb     | 29 ++++++---
 ..._freeform_additional_properties_request.rb | 29 ++++++---
 .../ruby-httpx/lib/petstore/models/user.rb    | 29 ++++++---
 .../ruby-httpx/lib/petstore/models/whale.rb   | 29 ++++++---
 .../ruby-httpx/lib/petstore/models/zebra.rb   | 29 ++++++---
 .../spec/custom/base_object_spec.rb           | 30 ++++++++++
 .../models/additional_properties_class.rb     | 29 ++++++---
 .../petstore/models/all_of_with_single_ref.rb | 29 ++++++---
 .../ruby/lib/petstore/models/animal.rb        | 29 ++++++---
 .../ruby/lib/petstore/models/api_response.rb  | 29 ++++++---
 .../models/array_of_array_of_number_only.rb   | 29 ++++++---
 .../petstore/models/array_of_number_only.rb   | 29 ++++++---
 .../ruby/lib/petstore/models/array_test.rb    | 29 ++++++---
 .../lib/petstore/models/capitalization.rb     | 29 ++++++---
 .../petstore/ruby/lib/petstore/models/cat.rb  | 32 ++++++----
 .../ruby/lib/petstore/models/category.rb      | 29 ++++++---
 .../ruby/lib/petstore/models/class_model.rb   | 29 ++++++---
 .../ruby/lib/petstore/models/client.rb        | 29 ++++++---
 .../lib/petstore/models/deprecated_object.rb  | 29 ++++++---
 .../petstore/ruby/lib/petstore/models/dog.rb  | 32 ++++++----
 .../ruby/lib/petstore/models/enum_arrays.rb   | 29 ++++++---
 .../ruby/lib/petstore/models/enum_test.rb     | 29 ++++++---
 .../fake_big_decimal_map200_response.rb       | 29 ++++++---
 .../petstore/ruby/lib/petstore/models/file.rb | 29 ++++++---
 .../petstore/models/file_schema_test_class.rb | 29 ++++++---
 .../petstore/ruby/lib/petstore/models/foo.rb  | 29 ++++++---
 .../models/foo_get_default_response.rb        | 29 ++++++---
 .../ruby/lib/petstore/models/format_test.rb   | 29 ++++++---
 .../lib/petstore/models/has_only_read_only.rb | 29 ++++++---
 .../petstore/models/health_check_result.rb    | 29 ++++++---
 .../petstore/ruby/lib/petstore/models/list.rb | 29 ++++++---
 .../ruby/lib/petstore/models/map_test.rb      | 29 ++++++---
 ...perties_and_additional_properties_class.rb | 29 ++++++---
 .../lib/petstore/models/model200_response.rb  | 29 ++++++---
 .../ruby/lib/petstore/models/model_return.rb  | 29 ++++++---
 .../petstore/ruby/lib/petstore/models/name.rb | 29 ++++++---
 .../lib/petstore/models/nullable_class.rb     | 29 ++++++---
 .../ruby/lib/petstore/models/number_only.rb   | 29 ++++++---
 .../models/object_with_deprecated_fields.rb   | 29 ++++++---
 .../ruby/lib/petstore/models/order.rb         | 29 ++++++---
 .../lib/petstore/models/outer_composite.rb    | 29 ++++++---
 .../models/outer_object_with_enum_property.rb | 29 ++++++---
 .../petstore/ruby/lib/petstore/models/pet.rb  | 29 ++++++---
 .../petstore/models/property_name_mapping.rb  | 29 ++++++---
 .../lib/petstore/models/read_only_first.rb    | 29 ++++++---
 .../lib/petstore/models/special_model_name.rb | 29 ++++++---
 .../petstore/ruby/lib/petstore/models/tag.rb  | 29 ++++++---
 ..._freeform_additional_properties_request.rb | 29 ++++++---
 .../petstore/ruby/lib/petstore/models/user.rb | 29 ++++++---
 .../ruby/lib/petstore/models/whale.rb         | 29 ++++++---
 .../ruby/lib/petstore/models/zebra.rb         | 29 ++++++---
 .../ruby/spec/custom/base_object_spec.rb      | 30 ++++++++++
 .../lib/petstore/models/array_alias.rb        | 41 ++++++++-----
 .../lib/petstore/models/map_alias.rb          | 29 ++++++---
 220 files changed, 4699 insertions(+), 1764 deletions(-)

diff --git a/modules/openapi-generator/src/main/resources/ruby-client/base_object.mustache b/modules/openapi-generator/src/main/resources/ruby-client/base_object.mustache
index d752c497c42c..68767dfcfb7c 100644
--- a/modules/openapi-generator/src/main/resources/ruby-client/base_object.mustache
+++ b/modules/openapi-generator/src/main/resources/ruby-client/base_object.mustache
@@ -3,22 +3,21 @@
     # @return [Object] Returns the model itself
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
-      {{#parent}}
-      super(attributes)
-      {{/parent}}
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -27,11 +26,12 @@
     # Returns the object in the form of hash
     # @return [Hash] Returns the object in the form of hash
     def to_hash
-      hash = {{^parent}}{}{{/parent}}{{#parent}}super{{/parent}}
-      self.class.attribute_map.each_pair do |attr, param|
+      hash = {}
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/modules/openapi-generator/src/main/resources/ruby-client/partial_model_generic.mustache b/modules/openapi-generator/src/main/resources/ruby-client/partial_model_generic.mustache
index d5ef9e8ab420..05e8b0bf0c78 100644
--- a/modules/openapi-generator/src/main/resources/ruby-client/partial_model_generic.mustache
+++ b/modules/openapi-generator/src/main/resources/ruby-client/partial_model_generic.mustache
@@ -42,17 +42,17 @@
       }
     end
 
-    # Returns attribute mapping this model knows about{{#parent}}, including the ones defined in its parent(s){{/parent}}
+    # Returns attribute mapping this model knows about{{#parentModel}}, including the ones defined in its parent(s){{/parentModel}}
     def self.acceptable_attribute_map
-      {{^parent}}
+      {{^parentModel}}
       attribute_map
-      {{/parent}}
-      {{#parent}}
+      {{/parentModel}}
+      {{#parentModel}}
       superclass.acceptable_attribute_map.merge(attribute_map)
-      {{/parent}}
+      {{/parentModel}}
     end
 
-    # Returns all the JSON keys this model knows about{{#parent}}, including the ones defined in its parent(s){{/parent}}
+    # Returns all the JSON keys this model knows about{{#parentModel}}, including the ones defined in its parent(s){{/parentModel}}
     def self.acceptable_attributes
       acceptable_attribute_map.values
     end
@@ -77,6 +77,26 @@
       ])
     end
 
+    # Returns attribute type mapping{{#parentModel}}, including the ones defined in its parent(s){{/parentModel}}
+    def self.acceptable_openapi_types
+      {{^parentModel}}
+      openapi_types
+      {{/parentModel}}
+      {{#parentModel}}
+      superclass.acceptable_openapi_types.merge(openapi_types)
+      {{/parentModel}}
+    end
+
+    # Returns the nullable attributes{{#parentModel}}, including the ones defined in its parent(s) that it does not redeclare{{/parentModel}}
+    def self.acceptable_openapi_nullable
+      {{^parentModel}}
+      openapi_nullable
+      {{/parentModel}}
+      {{#parentModel}}
+      (superclass.acceptable_openapi_nullable - attribute_map.keys) | openapi_nullable
+      {{/parentModel}}
+    end
+
     {{#anyOf}}
     {{#-first}}
     # List of class defined in anyOf (OpenAPI v3)
@@ -127,11 +147,11 @@
         end
         h[k.to_sym] = v
       }
-      {{#parent}}
+      {{#parentModel}}
 
       # call parent's initialize
       super(attributes)
-      {{/parent}}
+      {{/parentModel}}
       {{#vars}}
 
       if attributes.key?(:'{{{name}}}')
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/ruby/RubyClientCodegenTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/ruby/RubyClientCodegenTest.java
index f67bb6720788..a9914a9b8acf 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/ruby/RubyClientCodegenTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/ruby/RubyClientCodegenTest.java
@@ -26,12 +26,14 @@
 import org.openapitools.codegen.model.ModelMap;
 import org.openapitools.codegen.model.OperationMap;
 import org.openapitools.codegen.model.OperationsMap;
+import org.openapitools.codegen.utils.ModelUtils;
 import org.testng.Assert;
 import org.testng.annotations.Test;
 
 import java.io.File;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.*;
 import java.util.stream.Collectors;
 
@@ -799,4 +801,61 @@ public void testQueryParamJsonSerializationSetsQueryIsJsonMimeType() {
         assertTrue(op.queryParams.stream().allMatch(p -> p.queryIsJsonMimeType),
                 "All content:application/json query params should have queryIsJsonMimeType=true");
     }
+
+    @Test(description = "an allOf child's build_from_hash and to_hash include the attributes inherited from its parents")
+    public void testBuildFromHashMapsInheritedAttributes() throws Exception {
+        final File output = Files.createTempDirectory("test").toFile();
+        output.deleteOnExit();
+
+        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/allOf_composition_discriminator.yaml");
+        CodegenConfig codegenConfig = new RubyClientCodegen();
+        codegenConfig.setOutputDir(output.getAbsolutePath());
+
+        ClientOptInput clientOptInput = new ClientOptInput().openAPI(openAPI).config(codegenConfig);
+        new DefaultGenerator().opts(clientOptInput).generate();
+
+        // Lizard < Reptile < Pet: types and nullability merge along the ancestry, the nearest declaration wins
+        Path lizard = new File(output, "lib/openapi_client/models/lizard.rb").toPath();
+        TestUtils.assertFileContains(lizard,
+                "superclass.acceptable_openapi_types.merge(openapi_types)",
+                "(superclass.acceptable_openapi_nullable - attribute_map.keys) | openapi_nullable");
+        // build_from_hash and to_hash use the merged maps
+        TestUtils.assertFileContains(lizard,
+                "acceptable_openapi_types.each_pair do |key, type|",
+                "self.class.acceptable_attribute_map.each_pair do |attr, param|",
+                "is_nullable = self.class.acceptable_openapi_nullable.include?(attr)");
+        // the super call that built and discarded a second instance is gone
+        TestUtils.assertFileNotContains(lizard, "super(attributes)\n      attributes = attributes.transform_keys(&:to_sym)");
+        // a root model has no parent to merge
+        TestUtils.assertFileNotContains(new File(output, "lib/openapi_client/models/pet.rb").toPath(), "superclass.acceptable_openapi_types");
+        // a generated parent still receives the initializer call
+        TestUtils.assertFileContains(lizard, "# call parent's initialize\n      super(attributes)");
+    }
+
+    @Test(description = "a model whose superclass is not a generated model (an alias to an array) does not delegate to it")
+    public void testAliasModelDoesNotDelegateToItsBuiltInSuperclass() throws Exception {
+        final File output = Files.createTempDirectory("test").toFile();
+        output.deleteOnExit();
+
+        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/features/generate-alias-as-model.yaml");
+        CodegenConfig codegenConfig = new RubyClientCodegen();
+        codegenConfig.setOutputDir(output.getAbsolutePath());
+
+        ClientOptInput clientOptInput = new ClientOptInput().openAPI(openAPI).config(codegenConfig);
+        ModelUtils.setGenerateAliasAsModel(true);
+        try {
+            new DefaultGenerator().opts(clientOptInput).generate();
+        } finally {
+            ModelUtils.setGenerateAliasAsModel(false);
+        }
+
+        // ArrayAlias < Array: Array has none of the helpers, so each one is its own base case
+        Path arrayAlias = new File(output, "lib/openapi_client/models/array_alias.rb").toPath();
+        TestUtils.assertFileContains(arrayAlias,
+                "class ArrayAlias < Array",
+                "def self.acceptable_attribute_map\n      attribute_map\n    end",
+                "def self.acceptable_openapi_types\n      openapi_types\n    end",
+                "def self.acceptable_openapi_nullable\n      openapi_nullable\n    end");
+        TestUtils.assertFileNotContains(arrayAlias, "superclass.", "super(attributes)");
+    }
 }
diff --git a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/bird.rb b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/bird.rb
index 791ff7830e90..9f03a6daeca5 100644
--- a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/bird.rb
+++ b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/bird.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/category.rb b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/category.rb
index 2ae2f25e7bb6..a9e3fae3e988 100644
--- a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/category.rb
+++ b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/category.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/data_query.rb b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/data_query.rb
index 1a31b4d3e83f..0575446c351f 100644
--- a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/data_query.rb
+++ b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/data_query.rb
@@ -80,6 +80,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping, including the ones defined in its parent(s)
+    def self.acceptable_openapi_types
+      superclass.acceptable_openapi_types.merge(openapi_types)
+    end
+
+    # Returns the nullable attributes, including the ones defined in its parent(s) that it does not redeclare
+    def self.acceptable_openapi_nullable
+      (superclass.acceptable_openapi_nullable - attribute_map.keys) | openapi_nullable
+    end
+
     # List of class defined in allOf (OpenAPI v3)
     def self.openapi_all_of
       [
@@ -161,20 +171,21 @@ def hash
     # @return [Object] Returns the model itself
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
-      super(attributes)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -183,11 +194,12 @@ def self.build_from_hash(attributes)
     # Returns the object in the form of hash
     # @return [Hash] Returns the object in the form of hash
     def to_hash
-      hash = super
-      self.class.attribute_map.each_pair do |attr, param|
+      hash = {}
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/default_value.rb b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/default_value.rb
index 9dbb442bb860..451707d0eeb9 100644
--- a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/default_value.rb
+++ b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/default_value.rb
@@ -101,6 +101,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -212,18 +222,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -233,10 +245,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/number_properties_only.rb b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/number_properties_only.rb
index 46b63c582964..20ace6a8baad 100644
--- a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/number_properties_only.rb
+++ b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/number_properties_only.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -155,18 +165,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -176,10 +188,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/pet.rb b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/pet.rb
index d1a334676d56..c756e2ce6b41 100644
--- a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/pet.rb
+++ b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/pet.rb
@@ -90,6 +90,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -227,18 +237,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -248,10 +260,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/query.rb b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/query.rb
index 7598d312f1dd..1e1b31de201b 100644
--- a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/query.rb
+++ b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/query.rb
@@ -74,6 +74,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -143,18 +153,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -164,10 +176,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/tag.rb b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/tag.rb
index d087eafa1516..e0d61143d2f0 100644
--- a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/tag.rb
+++ b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/tag.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/test_form_object_multipart_request_marker.rb b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/test_form_object_multipart_request_marker.rb
index 1b00e10e7dc3..6b33437e3258 100644
--- a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/test_form_object_multipart_request_marker.rb
+++ b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/test_form_object_multipart_request_marker.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.rb b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.rb
index 02afae09bce2..04a9bd521165 100644
--- a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.rb
+++ b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.rb
@@ -59,6 +59,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # List of class defined in allOf (OpenAPI v3)
     def self.openapi_all_of
       [
@@ -144,18 +154,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -165,10 +177,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/test_query_style_form_explode_true_array_string_query_object_parameter.rb b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/test_query_style_form_explode_true_array_string_query_object_parameter.rb
index fa9520a4f16c..3c67a8e0f2a9 100644
--- a/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/test_query_style_form_explode_true_array_string_query_object_parameter.rb
+++ b/samples/client/echo_api/ruby-faraday/lib/openapi_client/models/test_query_style_form_explode_true_array_string_query_object_parameter.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/bird.rb b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/bird.rb
index 791ff7830e90..9f03a6daeca5 100644
--- a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/bird.rb
+++ b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/bird.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/category.rb b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/category.rb
index 2ae2f25e7bb6..a9e3fae3e988 100644
--- a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/category.rb
+++ b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/category.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/data_query.rb b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/data_query.rb
index 1a31b4d3e83f..0575446c351f 100644
--- a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/data_query.rb
+++ b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/data_query.rb
@@ -80,6 +80,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping, including the ones defined in its parent(s)
+    def self.acceptable_openapi_types
+      superclass.acceptable_openapi_types.merge(openapi_types)
+    end
+
+    # Returns the nullable attributes, including the ones defined in its parent(s) that it does not redeclare
+    def self.acceptable_openapi_nullable
+      (superclass.acceptable_openapi_nullable - attribute_map.keys) | openapi_nullable
+    end
+
     # List of class defined in allOf (OpenAPI v3)
     def self.openapi_all_of
       [
@@ -161,20 +171,21 @@ def hash
     # @return [Object] Returns the model itself
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
-      super(attributes)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -183,11 +194,12 @@ def self.build_from_hash(attributes)
     # Returns the object in the form of hash
     # @return [Hash] Returns the object in the form of hash
     def to_hash
-      hash = super
-      self.class.attribute_map.each_pair do |attr, param|
+      hash = {}
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/default_value.rb b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/default_value.rb
index 9dbb442bb860..451707d0eeb9 100644
--- a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/default_value.rb
+++ b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/default_value.rb
@@ -101,6 +101,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -212,18 +222,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -233,10 +245,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/number_properties_only.rb b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/number_properties_only.rb
index 46b63c582964..20ace6a8baad 100644
--- a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/number_properties_only.rb
+++ b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/number_properties_only.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -155,18 +165,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -176,10 +188,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/pet.rb b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/pet.rb
index d1a334676d56..c756e2ce6b41 100644
--- a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/pet.rb
+++ b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/pet.rb
@@ -90,6 +90,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -227,18 +237,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -248,10 +260,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/query.rb b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/query.rb
index 7598d312f1dd..1e1b31de201b 100644
--- a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/query.rb
+++ b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/query.rb
@@ -74,6 +74,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -143,18 +153,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -164,10 +176,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/tag.rb b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/tag.rb
index d087eafa1516..e0d61143d2f0 100644
--- a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/tag.rb
+++ b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/tag.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/test_form_object_multipart_request_marker.rb b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/test_form_object_multipart_request_marker.rb
index 1b00e10e7dc3..6b33437e3258 100644
--- a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/test_form_object_multipart_request_marker.rb
+++ b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/test_form_object_multipart_request_marker.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.rb b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.rb
index 02afae09bce2..04a9bd521165 100644
--- a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.rb
+++ b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.rb
@@ -59,6 +59,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # List of class defined in allOf (OpenAPI v3)
     def self.openapi_all_of
       [
@@ -144,18 +154,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -165,10 +177,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/test_query_style_form_explode_true_array_string_query_object_parameter.rb b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/test_query_style_form_explode_true_array_string_query_object_parameter.rb
index fa9520a4f16c..3c67a8e0f2a9 100644
--- a/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/test_query_style_form_explode_true_array_string_query_object_parameter.rb
+++ b/samples/client/echo_api/ruby-httpx/lib/openapi_client/models/test_query_style_form_explode_true_array_string_query_object_parameter.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/bird.rb b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/bird.rb
index 791ff7830e90..9f03a6daeca5 100644
--- a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/bird.rb
+++ b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/bird.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/category.rb b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/category.rb
index 2ae2f25e7bb6..a9e3fae3e988 100644
--- a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/category.rb
+++ b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/category.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/data_query.rb b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/data_query.rb
index 1a31b4d3e83f..0575446c351f 100644
--- a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/data_query.rb
+++ b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/data_query.rb
@@ -80,6 +80,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping, including the ones defined in its parent(s)
+    def self.acceptable_openapi_types
+      superclass.acceptable_openapi_types.merge(openapi_types)
+    end
+
+    # Returns the nullable attributes, including the ones defined in its parent(s) that it does not redeclare
+    def self.acceptable_openapi_nullable
+      (superclass.acceptable_openapi_nullable - attribute_map.keys) | openapi_nullable
+    end
+
     # List of class defined in allOf (OpenAPI v3)
     def self.openapi_all_of
       [
@@ -161,20 +171,21 @@ def hash
     # @return [Object] Returns the model itself
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
-      super(attributes)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -183,11 +194,12 @@ def self.build_from_hash(attributes)
     # Returns the object in the form of hash
     # @return [Hash] Returns the object in the form of hash
     def to_hash
-      hash = super
-      self.class.attribute_map.each_pair do |attr, param|
+      hash = {}
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/default_value.rb b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/default_value.rb
index 9dbb442bb860..451707d0eeb9 100644
--- a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/default_value.rb
+++ b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/default_value.rb
@@ -101,6 +101,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -212,18 +222,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -233,10 +245,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/number_properties_only.rb b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/number_properties_only.rb
index 46b63c582964..20ace6a8baad 100644
--- a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/number_properties_only.rb
+++ b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/number_properties_only.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -155,18 +165,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -176,10 +188,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/pet.rb b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/pet.rb
index d1a334676d56..c756e2ce6b41 100644
--- a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/pet.rb
+++ b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/pet.rb
@@ -90,6 +90,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -227,18 +237,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -248,10 +260,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/query.rb b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/query.rb
index 7598d312f1dd..1e1b31de201b 100644
--- a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/query.rb
+++ b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/query.rb
@@ -74,6 +74,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -143,18 +153,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -164,10 +176,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/tag.rb b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/tag.rb
index d087eafa1516..e0d61143d2f0 100644
--- a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/tag.rb
+++ b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/tag.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/test_form_object_multipart_request_marker.rb b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/test_form_object_multipart_request_marker.rb
index 1b00e10e7dc3..6b33437e3258 100644
--- a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/test_form_object_multipart_request_marker.rb
+++ b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/test_form_object_multipart_request_marker.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.rb b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.rb
index 02afae09bce2..04a9bd521165 100644
--- a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.rb
+++ b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.rb
@@ -59,6 +59,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # List of class defined in allOf (OpenAPI v3)
     def self.openapi_all_of
       [
@@ -144,18 +154,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -165,10 +177,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/test_query_style_form_explode_true_array_string_query_object_parameter.rb b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/test_query_style_form_explode_true_array_string_query_object_parameter.rb
index fa9520a4f16c..3c67a8e0f2a9 100644
--- a/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/test_query_style_form_explode_true_array_string_query_object_parameter.rb
+++ b/samples/client/echo_api/ruby-typhoeus/lib/openapi_client/models/test_query_style_form_explode_true_array_string_query_object_parameter.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/additional_properties_class.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/additional_properties_class.rb
index 9b823593d156..a240cadf547e 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/additional_properties_class.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/additional_properties_class.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -122,18 +132,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -143,10 +155,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/all_of_with_single_ref.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/all_of_with_single_ref.rb
index 600c974fa1e5..9977e0212627 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/all_of_with_single_ref.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/all_of_with_single_ref.rb
@@ -73,6 +73,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -140,18 +150,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -161,10 +173,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/animal.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/animal.rb
index 21d89bccb837..b58dbb506d4e 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/animal.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/animal.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # discriminator's property name in OpenAPI v3
     def self.openapi_discriminator_name
       :'class_name'
@@ -142,18 +152,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -163,10 +175,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/api_response.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/api_response.rb
index bbbaf9358be2..6b8e2bf4005f 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/api_response.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/api_response.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -127,18 +137,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -148,10 +160,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/array_of_array_of_number_only.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/array_of_array_of_number_only.rb
index e20b1728d130..40b968094257 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/array_of_array_of_number_only.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/array_of_array_of_number_only.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/array_of_number_only.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/array_of_number_only.rb
index 63890ff64424..6b9bc3627785 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/array_of_number_only.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/array_of_number_only.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/array_test.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/array_test.rb
index c74060151e07..fc5e9d297766 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/array_test.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/array_test.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -161,18 +171,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -182,10 +194,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/capitalization.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/capitalization.rb
index e0bbeb211eb3..9031ca3f7d51 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/capitalization.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/capitalization.rb
@@ -68,6 +68,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -155,18 +165,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -176,10 +188,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/cat.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/cat.rb
index a84dc5038bef..a1f3de5272b6 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/cat.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/cat.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping, including the ones defined in its parent(s)
+    def self.acceptable_openapi_types
+      superclass.acceptable_openapi_types.merge(openapi_types)
+    end
+
+    # Returns the nullable attributes, including the ones defined in its parent(s) that it does not redeclare
+    def self.acceptable_openapi_nullable
+      (superclass.acceptable_openapi_nullable - attribute_map.keys) | openapi_nullable
+    end
+
     # List of class defined in allOf (OpenAPI v3)
     def self.openapi_all_of
       [
@@ -118,20 +128,21 @@ def hash
     # @return [Object] Returns the model itself
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
-      super(attributes)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -140,11 +151,12 @@ def self.build_from_hash(attributes)
     # Returns the object in the form of hash
     # @return [Hash] Returns the object in the form of hash
     def to_hash
-      hash = super
-      self.class.attribute_map.each_pair do |attr, param|
+      hash = {}
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/category.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/category.rb
index 2f2b7f1a5785..a5af1c3f9acc 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/category.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/category.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -135,18 +145,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -156,10 +168,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/child_with_nullable.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/child_with_nullable.rb
index a7c86c864e6e..1e4671c79c42 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/child_with_nullable.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/child_with_nullable.rb
@@ -69,6 +69,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping, including the ones defined in its parent(s)
+    def self.acceptable_openapi_types
+      superclass.acceptable_openapi_types.merge(openapi_types)
+    end
+
+    # Returns the nullable attributes, including the ones defined in its parent(s) that it does not redeclare
+    def self.acceptable_openapi_nullable
+      (superclass.acceptable_openapi_nullable - attribute_map.keys) | openapi_nullable
+    end
+
     # List of class defined in allOf (OpenAPI v3)
     def self.openapi_all_of
       [
@@ -140,20 +150,21 @@ def hash
     # @return [Object] Returns the model itself
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
-      super(attributes)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -162,11 +173,12 @@ def self.build_from_hash(attributes)
     # Returns the object in the form of hash
     # @return [Hash] Returns the object in the form of hash
     def to_hash
-      hash = super
-      self.class.attribute_map.each_pair do |attr, param|
+      hash = {}
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/class_model.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/class_model.rb
index fafd11df773a..4e611ee27f3e 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/class_model.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/class_model.rb
@@ -48,6 +48,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -110,18 +120,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -131,10 +143,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/client.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/client.rb
index a349b7251d7b..f775d0f1d542 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/client.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/client.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/deprecated_object.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/deprecated_object.rb
index 9f1ee6720cab..bdc86013c848 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/deprecated_object.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/deprecated_object.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/dog.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/dog.rb
index 522e1a72f47e..2e8f95136f9a 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/dog.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/dog.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping, including the ones defined in its parent(s)
+    def self.acceptable_openapi_types
+      superclass.acceptable_openapi_types.merge(openapi_types)
+    end
+
+    # Returns the nullable attributes, including the ones defined in its parent(s) that it does not redeclare
+    def self.acceptable_openapi_nullable
+      (superclass.acceptable_openapi_nullable - attribute_map.keys) | openapi_nullable
+    end
+
     # List of class defined in allOf (OpenAPI v3)
     def self.openapi_all_of
       [
@@ -118,20 +128,21 @@ def hash
     # @return [Object] Returns the model itself
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
-      super(attributes)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -140,11 +151,12 @@ def self.build_from_hash(attributes)
     # Returns the object in the form of hash
     # @return [Hash] Returns the object in the form of hash
     def to_hash
-      hash = super
-      self.class.attribute_map.each_pair do |attr, param|
+      hash = {}
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/enum_arrays.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/enum_arrays.rb
index 1f7c48bf859b..8058a6ac60bb 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/enum_arrays.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/enum_arrays.rb
@@ -73,6 +73,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -154,18 +164,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -175,10 +187,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/enum_test.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/enum_test.rb
index 5159875cb89b..3b3905c138a3 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/enum_test.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/enum_test.rb
@@ -98,6 +98,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -254,18 +264,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -275,10 +287,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/fake_big_decimal_map200_response.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/fake_big_decimal_map200_response.rb
index 6d5e47b59656..b7be6af6d90e 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/fake_big_decimal_map200_response.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/fake_big_decimal_map200_response.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -120,18 +130,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -141,10 +153,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/file.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/file.rb
index 219237eb3c07..4fac9978fcaa 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/file.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/file.rb
@@ -49,6 +49,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/file_schema_test_class.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/file_schema_test_class.rb
index 8fdab5a25e86..074c235ebe17 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/file_schema_test_class.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/file_schema_test_class.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -120,18 +130,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -141,10 +153,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/foo.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/foo.rb
index ceb5b7497955..811726434b54 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/foo.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/foo.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/foo_get_default_response.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/foo_get_default_response.rb
index 42538a14e2cb..61d044ad8f26 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/foo_get_default_response.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/foo_get_default_response.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/format_test.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/format_test.rb
index 03a4e130a8f9..6760f6807c59 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/format_test.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/format_test.rb
@@ -109,6 +109,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -525,18 +535,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -546,10 +558,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/has_only_read_only.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/has_only_read_only.rb
index cc584c09e54f..604a3da147bd 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/has_only_read_only.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/has_only_read_only.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/health_check_result.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/health_check_result.rb
index a66e1b71331d..0792044db072 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/health_check_result.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/health_check_result.rb
@@ -49,6 +49,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/list.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/list.rb
index 2dc658065278..ecc8eb8aafc5 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/list.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/list.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/map_test.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/map_test.rb
index 78c5472f24ae..eca01649a52a 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/map_test.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/map_test.rb
@@ -81,6 +81,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -166,18 +176,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -187,10 +199,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/mixed_properties_and_additional_properties_class.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/mixed_properties_and_additional_properties_class.rb
index bf1d3768951b..060c8488652f 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/mixed_properties_and_additional_properties_class.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/mixed_properties_and_additional_properties_class.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -129,18 +139,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -150,10 +162,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/model200_response.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/model200_response.rb
index 9cff83ced2c9..2ea5253eb3d4 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/model200_response.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/model200_response.rb
@@ -52,6 +52,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -119,18 +129,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -140,10 +152,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/model_return.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/model_return.rb
index d520a45c2040..c2b6ac11c2e9 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/model_return.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/model_return.rb
@@ -48,6 +48,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -110,18 +120,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -131,10 +143,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/name.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/name.rb
index 45b01b5746d3..c989368e6597 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/name.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/name.rb
@@ -60,6 +60,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -154,18 +164,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -175,10 +187,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/nullable_class.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/nullable_class.rb
index f81fb17f118a..de5510060a65 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/nullable_class.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/nullable_class.rb
@@ -101,6 +101,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -230,18 +240,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -251,10 +263,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/number_only.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/number_only.rb
index 9bf457dfd188..b4fb53e2c3d3 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/number_only.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/number_only.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/object_with_deprecated_fields.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/object_with_deprecated_fields.rb
index dceda346bd70..3819fef7a58b 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/object_with_deprecated_fields.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/object_with_deprecated_fields.rb
@@ -59,6 +59,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -138,18 +148,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -159,10 +171,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/order.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/order.rb
index f7e7b4eb9117..8cebfcefa34e 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/order.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/order.rb
@@ -90,6 +90,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -191,18 +201,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -212,10 +224,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_composite.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_composite.rb
index 2245e8512600..afa9203ebde9 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_composite.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_composite.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -127,18 +137,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -148,10 +160,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_object_with_enum_property.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_object_with_enum_property.rb
index 8ffad20f8d89..1fd79229d4f6 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_object_with_enum_property.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/outer_object_with_enum_property.rb
@@ -69,6 +69,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -148,18 +158,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -169,10 +181,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/parent_with_nullable.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/parent_with_nullable.rb
index dde93af94488..5af979aaa167 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/parent_with_nullable.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/parent_with_nullable.rb
@@ -74,6 +74,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # discriminator's property name in OpenAPI v3
     def self.openapi_discriminator_name
       :'type'
@@ -158,18 +168,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -179,10 +191,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/pet.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/pet.rb
index e3594a1fb052..5a86112a15cf 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/pet.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/pet.rb
@@ -90,6 +90,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -227,18 +237,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -248,10 +260,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/read_only_first.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/read_only_first.rb
index c2121474ebb7..d008b4369a91 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/read_only_first.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/read_only_first.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/special_model_name.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/special_model_name.rb
index 9569fbfd13dd..b6d4135991be 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/special_model_name.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/special_model_name.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/tag.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/tag.rb
index 6d6f57468181..22589f4e58b3 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/tag.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/tag.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/test_inline_freeform_additional_properties_request.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/test_inline_freeform_additional_properties_request.rb
index dc481c119d22..9e52e64e286b 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/test_inline_freeform_additional_properties_request.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/test_inline_freeform_additional_properties_request.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-autoload/lib/petstore/models/user.rb b/samples/client/petstore/ruby-autoload/lib/petstore/models/user.rb
index 9b06f2ff6d7a..4b67db8214e2 100644
--- a/samples/client/petstore/ruby-autoload/lib/petstore/models/user.rb
+++ b/samples/client/petstore/ruby-autoload/lib/petstore/models/user.rb
@@ -76,6 +76,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -173,18 +183,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -194,10 +206,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/additional_properties_class.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/additional_properties_class.rb
index 9b823593d156..a240cadf547e 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/additional_properties_class.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/additional_properties_class.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -122,18 +132,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -143,10 +155,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/all_of_with_single_ref.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/all_of_with_single_ref.rb
index 600c974fa1e5..9977e0212627 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/all_of_with_single_ref.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/all_of_with_single_ref.rb
@@ -73,6 +73,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -140,18 +150,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -161,10 +173,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/animal.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/animal.rb
index 21d89bccb837..b58dbb506d4e 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/animal.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/animal.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # discriminator's property name in OpenAPI v3
     def self.openapi_discriminator_name
       :'class_name'
@@ -142,18 +152,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -163,10 +175,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/api_response.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/api_response.rb
index bbbaf9358be2..6b8e2bf4005f 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/api_response.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/api_response.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -127,18 +137,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -148,10 +160,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/array_of_array_of_number_only.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/array_of_array_of_number_only.rb
index e20b1728d130..40b968094257 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/array_of_array_of_number_only.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/array_of_array_of_number_only.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/array_of_number_only.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/array_of_number_only.rb
index 63890ff64424..6b9bc3627785 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/array_of_number_only.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/array_of_number_only.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/array_test.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/array_test.rb
index c74060151e07..fc5e9d297766 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/array_test.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/array_test.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -161,18 +171,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -182,10 +194,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/capitalization.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/capitalization.rb
index e0bbeb211eb3..9031ca3f7d51 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/capitalization.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/capitalization.rb
@@ -68,6 +68,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -155,18 +165,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -176,10 +188,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/cat.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/cat.rb
index a84dc5038bef..a1f3de5272b6 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/cat.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/cat.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping, including the ones defined in its parent(s)
+    def self.acceptable_openapi_types
+      superclass.acceptable_openapi_types.merge(openapi_types)
+    end
+
+    # Returns the nullable attributes, including the ones defined in its parent(s) that it does not redeclare
+    def self.acceptable_openapi_nullable
+      (superclass.acceptable_openapi_nullable - attribute_map.keys) | openapi_nullable
+    end
+
     # List of class defined in allOf (OpenAPI v3)
     def self.openapi_all_of
       [
@@ -118,20 +128,21 @@ def hash
     # @return [Object] Returns the model itself
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
-      super(attributes)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -140,11 +151,12 @@ def self.build_from_hash(attributes)
     # Returns the object in the form of hash
     # @return [Hash] Returns the object in the form of hash
     def to_hash
-      hash = super
-      self.class.attribute_map.each_pair do |attr, param|
+      hash = {}
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/category.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/category.rb
index 2f2b7f1a5785..a5af1c3f9acc 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/category.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/category.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -135,18 +145,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -156,10 +168,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/class_model.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/class_model.rb
index fafd11df773a..4e611ee27f3e 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/class_model.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/class_model.rb
@@ -48,6 +48,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -110,18 +120,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -131,10 +143,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/client.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/client.rb
index a349b7251d7b..f775d0f1d542 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/client.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/client.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/deprecated_object.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/deprecated_object.rb
index 9f1ee6720cab..bdc86013c848 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/deprecated_object.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/deprecated_object.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/dog.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/dog.rb
index 522e1a72f47e..2e8f95136f9a 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/dog.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/dog.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping, including the ones defined in its parent(s)
+    def self.acceptable_openapi_types
+      superclass.acceptable_openapi_types.merge(openapi_types)
+    end
+
+    # Returns the nullable attributes, including the ones defined in its parent(s) that it does not redeclare
+    def self.acceptable_openapi_nullable
+      (superclass.acceptable_openapi_nullable - attribute_map.keys) | openapi_nullable
+    end
+
     # List of class defined in allOf (OpenAPI v3)
     def self.openapi_all_of
       [
@@ -118,20 +128,21 @@ def hash
     # @return [Object] Returns the model itself
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
-      super(attributes)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -140,11 +151,12 @@ def self.build_from_hash(attributes)
     # Returns the object in the form of hash
     # @return [Hash] Returns the object in the form of hash
     def to_hash
-      hash = super
-      self.class.attribute_map.each_pair do |attr, param|
+      hash = {}
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/enum_arrays.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/enum_arrays.rb
index 1f7c48bf859b..8058a6ac60bb 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/enum_arrays.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/enum_arrays.rb
@@ -73,6 +73,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -154,18 +164,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -175,10 +187,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/enum_test.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/enum_test.rb
index 5159875cb89b..3b3905c138a3 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/enum_test.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/enum_test.rb
@@ -98,6 +98,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -254,18 +264,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -275,10 +287,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/fake_big_decimal_map200_response.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/fake_big_decimal_map200_response.rb
index 6d5e47b59656..b7be6af6d90e 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/fake_big_decimal_map200_response.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/fake_big_decimal_map200_response.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -120,18 +130,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -141,10 +153,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/file.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/file.rb
index 219237eb3c07..4fac9978fcaa 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/file.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/file.rb
@@ -49,6 +49,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/file_schema_test_class.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/file_schema_test_class.rb
index 8fdab5a25e86..074c235ebe17 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/file_schema_test_class.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/file_schema_test_class.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -120,18 +130,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -141,10 +153,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/foo.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/foo.rb
index ceb5b7497955..811726434b54 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/foo.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/foo.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/foo_get_default_response.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/foo_get_default_response.rb
index 42538a14e2cb..61d044ad8f26 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/foo_get_default_response.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/foo_get_default_response.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/format_test.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/format_test.rb
index 03a4e130a8f9..6760f6807c59 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/format_test.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/format_test.rb
@@ -109,6 +109,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -525,18 +535,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -546,10 +558,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/has_only_read_only.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/has_only_read_only.rb
index cc584c09e54f..604a3da147bd 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/has_only_read_only.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/has_only_read_only.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/health_check_result.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/health_check_result.rb
index a66e1b71331d..0792044db072 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/health_check_result.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/health_check_result.rb
@@ -49,6 +49,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/list.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/list.rb
index 2dc658065278..ecc8eb8aafc5 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/list.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/list.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/map_test.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/map_test.rb
index 78c5472f24ae..eca01649a52a 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/map_test.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/map_test.rb
@@ -81,6 +81,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -166,18 +176,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -187,10 +199,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/mixed_properties_and_additional_properties_class.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/mixed_properties_and_additional_properties_class.rb
index bf1d3768951b..060c8488652f 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/mixed_properties_and_additional_properties_class.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/mixed_properties_and_additional_properties_class.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -129,18 +139,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -150,10 +162,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/model200_response.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/model200_response.rb
index 9cff83ced2c9..2ea5253eb3d4 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/model200_response.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/model200_response.rb
@@ -52,6 +52,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -119,18 +129,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -140,10 +152,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/model_return.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/model_return.rb
index d520a45c2040..c2b6ac11c2e9 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/model_return.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/model_return.rb
@@ -48,6 +48,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -110,18 +120,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -131,10 +143,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/name.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/name.rb
index 45b01b5746d3..c989368e6597 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/name.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/name.rb
@@ -60,6 +60,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -154,18 +164,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -175,10 +187,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/nullable_class.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/nullable_class.rb
index f81fb17f118a..de5510060a65 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/nullable_class.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/nullable_class.rb
@@ -101,6 +101,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -230,18 +240,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -251,10 +263,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/number_only.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/number_only.rb
index 9bf457dfd188..b4fb53e2c3d3 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/number_only.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/number_only.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/object_with_deprecated_fields.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/object_with_deprecated_fields.rb
index dceda346bd70..3819fef7a58b 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/object_with_deprecated_fields.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/object_with_deprecated_fields.rb
@@ -59,6 +59,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -138,18 +148,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -159,10 +171,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/order.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/order.rb
index f7e7b4eb9117..8cebfcefa34e 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/order.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/order.rb
@@ -90,6 +90,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -191,18 +201,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -212,10 +224,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_composite.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_composite.rb
index 2245e8512600..afa9203ebde9 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_composite.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_composite.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -127,18 +137,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -148,10 +160,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_object_with_enum_property.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_object_with_enum_property.rb
index 8ffad20f8d89..1fd79229d4f6 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_object_with_enum_property.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/outer_object_with_enum_property.rb
@@ -69,6 +69,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -148,18 +158,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -169,10 +181,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/pet.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/pet.rb
index e3594a1fb052..5a86112a15cf 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/pet.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/pet.rb
@@ -90,6 +90,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -227,18 +237,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -248,10 +260,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/property_name_mapping.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/property_name_mapping.rb
index 8328edb9227a..82c1d3be0d08 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/property_name_mapping.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/property_name_mapping.rb
@@ -59,6 +59,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -136,18 +146,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -157,10 +169,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/read_only_first.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/read_only_first.rb
index c2121474ebb7..d008b4369a91 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/read_only_first.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/read_only_first.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/special_model_name.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/special_model_name.rb
index 9569fbfd13dd..b6d4135991be 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/special_model_name.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/special_model_name.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/tag.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/tag.rb
index 6d6f57468181..22589f4e58b3 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/tag.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/tag.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/test_inline_freeform_additional_properties_request.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/test_inline_freeform_additional_properties_request.rb
index dc481c119d22..9e52e64e286b 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/test_inline_freeform_additional_properties_request.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/test_inline_freeform_additional_properties_request.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/user.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/user.rb
index 9b06f2ff6d7a..4b67db8214e2 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/user.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/user.rb
@@ -76,6 +76,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -173,18 +183,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -194,10 +206,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/whale.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/whale.rb
index 23249be434e4..f29de72ecb1a 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/whale.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/whale.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -144,18 +154,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -165,10 +177,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/lib/petstore/models/zebra.rb b/samples/client/petstore/ruby-faraday/lib/petstore/models/zebra.rb
index 10e910f409f7..79771e498151 100644
--- a/samples/client/petstore/ruby-faraday/lib/petstore/models/zebra.rb
+++ b/samples/client/petstore/ruby-faraday/lib/petstore/models/zebra.rb
@@ -73,6 +73,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -169,18 +179,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -190,10 +202,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-faraday/spec/custom/base_object_spec.rb b/samples/client/petstore/ruby-faraday/spec/custom/base_object_spec.rb
index a046c5bd4e11..bc0ed63000b4 100644
--- a/samples/client/petstore/ruby-faraday/spec/custom/base_object_spec.rb
+++ b/samples/client/petstore/ruby-faraday/spec/custom/base_object_spec.rb
@@ -166,4 +166,34 @@ def initialize(attributes = {})
       expect(obj.to_hash).to eq(expect_data)
     end
   end
+
+  describe 'attributes inherited from an allOf parent' do
+    it 'build_from_hash and to_hash include the parent attributes' do
+      cat = Petstore::Cat.build_from_hash({ 'className' => 'Cat', 'color' => 'black', 'declawed' => true })
+
+      expect(cat).to be_instance_of(Petstore::Cat)
+      expect(cat.class_name).to eq('Cat')
+      expect(cat.color).to eq('black')
+      expect(cat.declawed).to eq(true)
+      expect(cat.to_hash).to eq({ className: 'Cat', color: 'black', declawed: true })
+    end
+
+    # passes on master too: guards that a subclass narrowing attribute_map is not handed its parent's attributes
+    it 'a subclass that narrows attribute_map is only handed the attributes it accepts' do
+      narrowed = Class.new(Petstore::Animal) do
+        def self.attribute_map
+          { :class_name => :className }
+        end
+
+        def self.openapi_types
+          { :class_name => :'String' }
+        end
+      end
+
+      obj = narrowed.build_from_hash({ 'className' => 'Cat', 'color' => 'black' })
+
+      expect(obj.class_name).to eq('Cat')
+      expect(obj.to_hash).to eq({ className: 'Cat' })
+    end
+  end
 end
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/additional_properties_class.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/additional_properties_class.rb
index 9b823593d156..a240cadf547e 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/additional_properties_class.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/additional_properties_class.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -122,18 +132,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -143,10 +155,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/all_of_with_single_ref.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/all_of_with_single_ref.rb
index 600c974fa1e5..9977e0212627 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/all_of_with_single_ref.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/all_of_with_single_ref.rb
@@ -73,6 +73,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -140,18 +150,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -161,10 +173,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/animal.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/animal.rb
index 21d89bccb837..b58dbb506d4e 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/animal.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/animal.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # discriminator's property name in OpenAPI v3
     def self.openapi_discriminator_name
       :'class_name'
@@ -142,18 +152,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -163,10 +175,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/api_response.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/api_response.rb
index bbbaf9358be2..6b8e2bf4005f 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/api_response.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/api_response.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -127,18 +137,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -148,10 +160,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/array_of_array_of_number_only.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/array_of_array_of_number_only.rb
index e20b1728d130..40b968094257 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/array_of_array_of_number_only.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/array_of_array_of_number_only.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/array_of_number_only.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/array_of_number_only.rb
index 63890ff64424..6b9bc3627785 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/array_of_number_only.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/array_of_number_only.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/array_test.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/array_test.rb
index c74060151e07..fc5e9d297766 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/array_test.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/array_test.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -161,18 +171,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -182,10 +194,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/capitalization.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/capitalization.rb
index e0bbeb211eb3..9031ca3f7d51 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/capitalization.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/capitalization.rb
@@ -68,6 +68,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -155,18 +165,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -176,10 +188,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/cat.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/cat.rb
index a84dc5038bef..a1f3de5272b6 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/cat.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/cat.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping, including the ones defined in its parent(s)
+    def self.acceptable_openapi_types
+      superclass.acceptable_openapi_types.merge(openapi_types)
+    end
+
+    # Returns the nullable attributes, including the ones defined in its parent(s) that it does not redeclare
+    def self.acceptable_openapi_nullable
+      (superclass.acceptable_openapi_nullable - attribute_map.keys) | openapi_nullable
+    end
+
     # List of class defined in allOf (OpenAPI v3)
     def self.openapi_all_of
       [
@@ -118,20 +128,21 @@ def hash
     # @return [Object] Returns the model itself
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
-      super(attributes)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -140,11 +151,12 @@ def self.build_from_hash(attributes)
     # Returns the object in the form of hash
     # @return [Hash] Returns the object in the form of hash
     def to_hash
-      hash = super
-      self.class.attribute_map.each_pair do |attr, param|
+      hash = {}
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/category.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/category.rb
index 2f2b7f1a5785..a5af1c3f9acc 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/category.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/category.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -135,18 +145,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -156,10 +168,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/class_model.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/class_model.rb
index fafd11df773a..4e611ee27f3e 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/class_model.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/class_model.rb
@@ -48,6 +48,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -110,18 +120,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -131,10 +143,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/client.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/client.rb
index a349b7251d7b..f775d0f1d542 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/client.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/client.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/deprecated_object.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/deprecated_object.rb
index 9f1ee6720cab..bdc86013c848 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/deprecated_object.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/deprecated_object.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/dog.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/dog.rb
index 522e1a72f47e..2e8f95136f9a 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/dog.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/dog.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping, including the ones defined in its parent(s)
+    def self.acceptable_openapi_types
+      superclass.acceptable_openapi_types.merge(openapi_types)
+    end
+
+    # Returns the nullable attributes, including the ones defined in its parent(s) that it does not redeclare
+    def self.acceptable_openapi_nullable
+      (superclass.acceptable_openapi_nullable - attribute_map.keys) | openapi_nullable
+    end
+
     # List of class defined in allOf (OpenAPI v3)
     def self.openapi_all_of
       [
@@ -118,20 +128,21 @@ def hash
     # @return [Object] Returns the model itself
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
-      super(attributes)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -140,11 +151,12 @@ def self.build_from_hash(attributes)
     # Returns the object in the form of hash
     # @return [Hash] Returns the object in the form of hash
     def to_hash
-      hash = super
-      self.class.attribute_map.each_pair do |attr, param|
+      hash = {}
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/enum_arrays.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/enum_arrays.rb
index 1f7c48bf859b..8058a6ac60bb 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/enum_arrays.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/enum_arrays.rb
@@ -73,6 +73,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -154,18 +164,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -175,10 +187,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/enum_test.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/enum_test.rb
index 5159875cb89b..3b3905c138a3 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/enum_test.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/enum_test.rb
@@ -98,6 +98,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -254,18 +264,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -275,10 +287,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/fake_big_decimal_map200_response.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/fake_big_decimal_map200_response.rb
index 6d5e47b59656..b7be6af6d90e 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/fake_big_decimal_map200_response.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/fake_big_decimal_map200_response.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -120,18 +130,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -141,10 +153,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/file.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/file.rb
index 219237eb3c07..4fac9978fcaa 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/file.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/file.rb
@@ -49,6 +49,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/file_schema_test_class.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/file_schema_test_class.rb
index 8fdab5a25e86..074c235ebe17 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/file_schema_test_class.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/file_schema_test_class.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -120,18 +130,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -141,10 +153,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/foo.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/foo.rb
index ceb5b7497955..811726434b54 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/foo.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/foo.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/foo_get_default_response.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/foo_get_default_response.rb
index 42538a14e2cb..61d044ad8f26 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/foo_get_default_response.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/foo_get_default_response.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/format_test.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/format_test.rb
index 03a4e130a8f9..6760f6807c59 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/format_test.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/format_test.rb
@@ -109,6 +109,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -525,18 +535,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -546,10 +558,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/has_only_read_only.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/has_only_read_only.rb
index cc584c09e54f..604a3da147bd 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/has_only_read_only.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/has_only_read_only.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/health_check_result.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/health_check_result.rb
index a66e1b71331d..0792044db072 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/health_check_result.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/health_check_result.rb
@@ -49,6 +49,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/list.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/list.rb
index 2dc658065278..ecc8eb8aafc5 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/list.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/list.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/map_test.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/map_test.rb
index 78c5472f24ae..eca01649a52a 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/map_test.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/map_test.rb
@@ -81,6 +81,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -166,18 +176,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -187,10 +199,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/mixed_properties_and_additional_properties_class.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/mixed_properties_and_additional_properties_class.rb
index bf1d3768951b..060c8488652f 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/mixed_properties_and_additional_properties_class.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/mixed_properties_and_additional_properties_class.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -129,18 +139,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -150,10 +162,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/model200_response.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/model200_response.rb
index 9cff83ced2c9..2ea5253eb3d4 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/model200_response.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/model200_response.rb
@@ -52,6 +52,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -119,18 +129,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -140,10 +152,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/model_return.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/model_return.rb
index d520a45c2040..c2b6ac11c2e9 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/model_return.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/model_return.rb
@@ -48,6 +48,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -110,18 +120,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -131,10 +143,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/name.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/name.rb
index 45b01b5746d3..c989368e6597 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/name.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/name.rb
@@ -60,6 +60,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -154,18 +164,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -175,10 +187,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/nullable_class.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/nullable_class.rb
index f81fb17f118a..de5510060a65 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/nullable_class.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/nullable_class.rb
@@ -101,6 +101,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -230,18 +240,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -251,10 +263,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/number_only.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/number_only.rb
index 9bf457dfd188..b4fb53e2c3d3 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/number_only.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/number_only.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/object_with_deprecated_fields.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/object_with_deprecated_fields.rb
index dceda346bd70..3819fef7a58b 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/object_with_deprecated_fields.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/object_with_deprecated_fields.rb
@@ -59,6 +59,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -138,18 +148,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -159,10 +171,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/order.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/order.rb
index f7e7b4eb9117..8cebfcefa34e 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/order.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/order.rb
@@ -90,6 +90,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -191,18 +201,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -212,10 +224,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/outer_composite.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/outer_composite.rb
index 2245e8512600..afa9203ebde9 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/outer_composite.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/outer_composite.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -127,18 +137,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -148,10 +160,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/outer_object_with_enum_property.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/outer_object_with_enum_property.rb
index 8ffad20f8d89..1fd79229d4f6 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/outer_object_with_enum_property.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/outer_object_with_enum_property.rb
@@ -69,6 +69,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -148,18 +158,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -169,10 +181,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/pet.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/pet.rb
index e3594a1fb052..5a86112a15cf 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/pet.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/pet.rb
@@ -90,6 +90,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -227,18 +237,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -248,10 +260,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/property_name_mapping.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/property_name_mapping.rb
index 8328edb9227a..82c1d3be0d08 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/property_name_mapping.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/property_name_mapping.rb
@@ -59,6 +59,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -136,18 +146,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -157,10 +169,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/read_only_first.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/read_only_first.rb
index c2121474ebb7..d008b4369a91 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/read_only_first.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/read_only_first.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/special_model_name.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/special_model_name.rb
index 9569fbfd13dd..b6d4135991be 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/special_model_name.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/special_model_name.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/tag.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/tag.rb
index 6d6f57468181..22589f4e58b3 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/tag.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/tag.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/test_inline_freeform_additional_properties_request.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/test_inline_freeform_additional_properties_request.rb
index dc481c119d22..9e52e64e286b 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/test_inline_freeform_additional_properties_request.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/test_inline_freeform_additional_properties_request.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/user.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/user.rb
index 9b06f2ff6d7a..4b67db8214e2 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/user.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/user.rb
@@ -76,6 +76,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -173,18 +183,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -194,10 +206,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/whale.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/whale.rb
index 23249be434e4..f29de72ecb1a 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/whale.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/whale.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -144,18 +154,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -165,10 +177,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/lib/petstore/models/zebra.rb b/samples/client/petstore/ruby-httpx/lib/petstore/models/zebra.rb
index 10e910f409f7..79771e498151 100644
--- a/samples/client/petstore/ruby-httpx/lib/petstore/models/zebra.rb
+++ b/samples/client/petstore/ruby-httpx/lib/petstore/models/zebra.rb
@@ -73,6 +73,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -169,18 +179,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -190,10 +202,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby-httpx/spec/custom/base_object_spec.rb b/samples/client/petstore/ruby-httpx/spec/custom/base_object_spec.rb
index a046c5bd4e11..bc0ed63000b4 100644
--- a/samples/client/petstore/ruby-httpx/spec/custom/base_object_spec.rb
+++ b/samples/client/petstore/ruby-httpx/spec/custom/base_object_spec.rb
@@ -166,4 +166,34 @@ def initialize(attributes = {})
       expect(obj.to_hash).to eq(expect_data)
     end
   end
+
+  describe 'attributes inherited from an allOf parent' do
+    it 'build_from_hash and to_hash include the parent attributes' do
+      cat = Petstore::Cat.build_from_hash({ 'className' => 'Cat', 'color' => 'black', 'declawed' => true })
+
+      expect(cat).to be_instance_of(Petstore::Cat)
+      expect(cat.class_name).to eq('Cat')
+      expect(cat.color).to eq('black')
+      expect(cat.declawed).to eq(true)
+      expect(cat.to_hash).to eq({ className: 'Cat', color: 'black', declawed: true })
+    end
+
+    # passes on master too: guards that a subclass narrowing attribute_map is not handed its parent's attributes
+    it 'a subclass that narrows attribute_map is only handed the attributes it accepts' do
+      narrowed = Class.new(Petstore::Animal) do
+        def self.attribute_map
+          { :class_name => :className }
+        end
+
+        def self.openapi_types
+          { :class_name => :'String' }
+        end
+      end
+
+      obj = narrowed.build_from_hash({ 'className' => 'Cat', 'color' => 'black' })
+
+      expect(obj.class_name).to eq('Cat')
+      expect(obj.to_hash).to eq({ className: 'Cat' })
+    end
+  end
 end
diff --git a/samples/client/petstore/ruby/lib/petstore/models/additional_properties_class.rb b/samples/client/petstore/ruby/lib/petstore/models/additional_properties_class.rb
index 9b823593d156..a240cadf547e 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/additional_properties_class.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/additional_properties_class.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -122,18 +132,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -143,10 +155,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/all_of_with_single_ref.rb b/samples/client/petstore/ruby/lib/petstore/models/all_of_with_single_ref.rb
index 600c974fa1e5..9977e0212627 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/all_of_with_single_ref.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/all_of_with_single_ref.rb
@@ -73,6 +73,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -140,18 +150,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -161,10 +173,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/animal.rb b/samples/client/petstore/ruby/lib/petstore/models/animal.rb
index 21d89bccb837..b58dbb506d4e 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/animal.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/animal.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # discriminator's property name in OpenAPI v3
     def self.openapi_discriminator_name
       :'class_name'
@@ -142,18 +152,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -163,10 +175,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/api_response.rb b/samples/client/petstore/ruby/lib/petstore/models/api_response.rb
index bbbaf9358be2..6b8e2bf4005f 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/api_response.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/api_response.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -127,18 +137,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -148,10 +160,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/array_of_array_of_number_only.rb b/samples/client/petstore/ruby/lib/petstore/models/array_of_array_of_number_only.rb
index e20b1728d130..40b968094257 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/array_of_array_of_number_only.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/array_of_array_of_number_only.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/array_of_number_only.rb b/samples/client/petstore/ruby/lib/petstore/models/array_of_number_only.rb
index 63890ff64424..6b9bc3627785 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/array_of_number_only.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/array_of_number_only.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/array_test.rb b/samples/client/petstore/ruby/lib/petstore/models/array_test.rb
index c74060151e07..fc5e9d297766 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/array_test.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/array_test.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -161,18 +171,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -182,10 +194,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/capitalization.rb b/samples/client/petstore/ruby/lib/petstore/models/capitalization.rb
index e0bbeb211eb3..9031ca3f7d51 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/capitalization.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/capitalization.rb
@@ -68,6 +68,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -155,18 +165,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -176,10 +188,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/cat.rb b/samples/client/petstore/ruby/lib/petstore/models/cat.rb
index a84dc5038bef..a1f3de5272b6 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/cat.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/cat.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping, including the ones defined in its parent(s)
+    def self.acceptable_openapi_types
+      superclass.acceptable_openapi_types.merge(openapi_types)
+    end
+
+    # Returns the nullable attributes, including the ones defined in its parent(s) that it does not redeclare
+    def self.acceptable_openapi_nullable
+      (superclass.acceptable_openapi_nullable - attribute_map.keys) | openapi_nullable
+    end
+
     # List of class defined in allOf (OpenAPI v3)
     def self.openapi_all_of
       [
@@ -118,20 +128,21 @@ def hash
     # @return [Object] Returns the model itself
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
-      super(attributes)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -140,11 +151,12 @@ def self.build_from_hash(attributes)
     # Returns the object in the form of hash
     # @return [Hash] Returns the object in the form of hash
     def to_hash
-      hash = super
-      self.class.attribute_map.each_pair do |attr, param|
+      hash = {}
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/category.rb b/samples/client/petstore/ruby/lib/petstore/models/category.rb
index 2f2b7f1a5785..a5af1c3f9acc 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/category.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/category.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -135,18 +145,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -156,10 +168,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/class_model.rb b/samples/client/petstore/ruby/lib/petstore/models/class_model.rb
index fafd11df773a..4e611ee27f3e 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/class_model.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/class_model.rb
@@ -48,6 +48,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -110,18 +120,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -131,10 +143,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/client.rb b/samples/client/petstore/ruby/lib/petstore/models/client.rb
index a349b7251d7b..f775d0f1d542 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/client.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/client.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/deprecated_object.rb b/samples/client/petstore/ruby/lib/petstore/models/deprecated_object.rb
index 9f1ee6720cab..bdc86013c848 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/deprecated_object.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/deprecated_object.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/dog.rb b/samples/client/petstore/ruby/lib/petstore/models/dog.rb
index 522e1a72f47e..2e8f95136f9a 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/dog.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/dog.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping, including the ones defined in its parent(s)
+    def self.acceptable_openapi_types
+      superclass.acceptable_openapi_types.merge(openapi_types)
+    end
+
+    # Returns the nullable attributes, including the ones defined in its parent(s) that it does not redeclare
+    def self.acceptable_openapi_nullable
+      (superclass.acceptable_openapi_nullable - attribute_map.keys) | openapi_nullable
+    end
+
     # List of class defined in allOf (OpenAPI v3)
     def self.openapi_all_of
       [
@@ -118,20 +128,21 @@ def hash
     # @return [Object] Returns the model itself
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
-      super(attributes)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -140,11 +151,12 @@ def self.build_from_hash(attributes)
     # Returns the object in the form of hash
     # @return [Hash] Returns the object in the form of hash
     def to_hash
-      hash = super
-      self.class.attribute_map.each_pair do |attr, param|
+      hash = {}
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/enum_arrays.rb b/samples/client/petstore/ruby/lib/petstore/models/enum_arrays.rb
index 1f7c48bf859b..8058a6ac60bb 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/enum_arrays.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/enum_arrays.rb
@@ -73,6 +73,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -154,18 +164,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -175,10 +187,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/enum_test.rb b/samples/client/petstore/ruby/lib/petstore/models/enum_test.rb
index 5159875cb89b..3b3905c138a3 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/enum_test.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/enum_test.rb
@@ -98,6 +98,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -254,18 +264,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -275,10 +287,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/fake_big_decimal_map200_response.rb b/samples/client/petstore/ruby/lib/petstore/models/fake_big_decimal_map200_response.rb
index 6d5e47b59656..b7be6af6d90e 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/fake_big_decimal_map200_response.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/fake_big_decimal_map200_response.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -120,18 +130,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -141,10 +153,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/file.rb b/samples/client/petstore/ruby/lib/petstore/models/file.rb
index 219237eb3c07..4fac9978fcaa 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/file.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/file.rb
@@ -49,6 +49,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/file_schema_test_class.rb b/samples/client/petstore/ruby/lib/petstore/models/file_schema_test_class.rb
index 8fdab5a25e86..074c235ebe17 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/file_schema_test_class.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/file_schema_test_class.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -120,18 +130,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -141,10 +153,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/foo.rb b/samples/client/petstore/ruby/lib/petstore/models/foo.rb
index ceb5b7497955..811726434b54 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/foo.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/foo.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/foo_get_default_response.rb b/samples/client/petstore/ruby/lib/petstore/models/foo_get_default_response.rb
index 42538a14e2cb..61d044ad8f26 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/foo_get_default_response.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/foo_get_default_response.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/format_test.rb b/samples/client/petstore/ruby/lib/petstore/models/format_test.rb
index 03a4e130a8f9..6760f6807c59 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/format_test.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/format_test.rb
@@ -109,6 +109,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -525,18 +535,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -546,10 +558,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/has_only_read_only.rb b/samples/client/petstore/ruby/lib/petstore/models/has_only_read_only.rb
index cc584c09e54f..604a3da147bd 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/has_only_read_only.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/has_only_read_only.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/health_check_result.rb b/samples/client/petstore/ruby/lib/petstore/models/health_check_result.rb
index a66e1b71331d..0792044db072 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/health_check_result.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/health_check_result.rb
@@ -49,6 +49,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -111,18 +121,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -132,10 +144,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/list.rb b/samples/client/petstore/ruby/lib/petstore/models/list.rb
index 2dc658065278..ecc8eb8aafc5 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/list.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/list.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/map_test.rb b/samples/client/petstore/ruby/lib/petstore/models/map_test.rb
index 78c5472f24ae..eca01649a52a 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/map_test.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/map_test.rb
@@ -81,6 +81,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -166,18 +176,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -187,10 +199,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/mixed_properties_and_additional_properties_class.rb b/samples/client/petstore/ruby/lib/petstore/models/mixed_properties_and_additional_properties_class.rb
index bf1d3768951b..060c8488652f 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/mixed_properties_and_additional_properties_class.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/mixed_properties_and_additional_properties_class.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -129,18 +139,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -150,10 +162,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/model200_response.rb b/samples/client/petstore/ruby/lib/petstore/models/model200_response.rb
index 9cff83ced2c9..2ea5253eb3d4 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/model200_response.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/model200_response.rb
@@ -52,6 +52,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -119,18 +129,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -140,10 +152,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/model_return.rb b/samples/client/petstore/ruby/lib/petstore/models/model_return.rb
index d520a45c2040..c2b6ac11c2e9 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/model_return.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/model_return.rb
@@ -48,6 +48,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -110,18 +120,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -131,10 +143,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/name.rb b/samples/client/petstore/ruby/lib/petstore/models/name.rb
index 45b01b5746d3..c989368e6597 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/name.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/name.rb
@@ -60,6 +60,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -154,18 +164,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -175,10 +187,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/nullable_class.rb b/samples/client/petstore/ruby/lib/petstore/models/nullable_class.rb
index f81fb17f118a..de5510060a65 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/nullable_class.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/nullable_class.rb
@@ -101,6 +101,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -230,18 +240,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -251,10 +263,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/number_only.rb b/samples/client/petstore/ruby/lib/petstore/models/number_only.rb
index 9bf457dfd188..b4fb53e2c3d3 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/number_only.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/number_only.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/object_with_deprecated_fields.rb b/samples/client/petstore/ruby/lib/petstore/models/object_with_deprecated_fields.rb
index dceda346bd70..3819fef7a58b 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/object_with_deprecated_fields.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/object_with_deprecated_fields.rb
@@ -59,6 +59,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -138,18 +148,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -159,10 +171,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/order.rb b/samples/client/petstore/ruby/lib/petstore/models/order.rb
index f7e7b4eb9117..8cebfcefa34e 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/order.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/order.rb
@@ -90,6 +90,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -191,18 +201,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -212,10 +224,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/outer_composite.rb b/samples/client/petstore/ruby/lib/petstore/models/outer_composite.rb
index 2245e8512600..afa9203ebde9 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/outer_composite.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/outer_composite.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -127,18 +137,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -148,10 +160,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/outer_object_with_enum_property.rb b/samples/client/petstore/ruby/lib/petstore/models/outer_object_with_enum_property.rb
index 8ffad20f8d89..1fd79229d4f6 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/outer_object_with_enum_property.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/outer_object_with_enum_property.rb
@@ -69,6 +69,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -148,18 +158,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -169,10 +181,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/pet.rb b/samples/client/petstore/ruby/lib/petstore/models/pet.rb
index e3594a1fb052..5a86112a15cf 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/pet.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/pet.rb
@@ -90,6 +90,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -227,18 +237,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -248,10 +260,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/property_name_mapping.rb b/samples/client/petstore/ruby/lib/petstore/models/property_name_mapping.rb
index 09e50b68dc06..ed1c46eeef88 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/property_name_mapping.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/property_name_mapping.rb
@@ -59,6 +59,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -136,18 +146,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -157,10 +169,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/read_only_first.rb b/samples/client/petstore/ruby/lib/petstore/models/read_only_first.rb
index c2121474ebb7..d008b4369a91 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/read_only_first.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/read_only_first.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/special_model_name.rb b/samples/client/petstore/ruby/lib/petstore/models/special_model_name.rb
index 9569fbfd13dd..b6d4135991be 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/special_model_name.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/special_model_name.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/tag.rb b/samples/client/petstore/ruby/lib/petstore/models/tag.rb
index 6d6f57468181..22589f4e58b3 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/tag.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/tag.rb
@@ -51,6 +51,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -118,18 +128,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -139,10 +151,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/test_inline_freeform_additional_properties_request.rb b/samples/client/petstore/ruby/lib/petstore/models/test_inline_freeform_additional_properties_request.rb
index dc481c119d22..9e52e64e286b 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/test_inline_freeform_additional_properties_request.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/test_inline_freeform_additional_properties_request.rb
@@ -47,6 +47,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -109,18 +119,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -130,10 +142,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/user.rb b/samples/client/petstore/ruby/lib/petstore/models/user.rb
index 9b06f2ff6d7a..4b67db8214e2 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/user.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/user.rb
@@ -76,6 +76,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -173,18 +183,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -194,10 +206,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/whale.rb b/samples/client/petstore/ruby/lib/petstore/models/whale.rb
index 23249be434e4..f29de72ecb1a 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/whale.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/whale.rb
@@ -55,6 +55,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -144,18 +154,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -165,10 +177,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/lib/petstore/models/zebra.rb b/samples/client/petstore/ruby/lib/petstore/models/zebra.rb
index 10e910f409f7..79771e498151 100644
--- a/samples/client/petstore/ruby/lib/petstore/models/zebra.rb
+++ b/samples/client/petstore/ruby/lib/petstore/models/zebra.rb
@@ -73,6 +73,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -169,18 +179,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -190,10 +202,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/client/petstore/ruby/spec/custom/base_object_spec.rb b/samples/client/petstore/ruby/spec/custom/base_object_spec.rb
index a046c5bd4e11..bc0ed63000b4 100644
--- a/samples/client/petstore/ruby/spec/custom/base_object_spec.rb
+++ b/samples/client/petstore/ruby/spec/custom/base_object_spec.rb
@@ -166,4 +166,34 @@ def initialize(attributes = {})
       expect(obj.to_hash).to eq(expect_data)
     end
   end
+
+  describe 'attributes inherited from an allOf parent' do
+    it 'build_from_hash and to_hash include the parent attributes' do
+      cat = Petstore::Cat.build_from_hash({ 'className' => 'Cat', 'color' => 'black', 'declawed' => true })
+
+      expect(cat).to be_instance_of(Petstore::Cat)
+      expect(cat.class_name).to eq('Cat')
+      expect(cat.color).to eq('black')
+      expect(cat.declawed).to eq(true)
+      expect(cat.to_hash).to eq({ className: 'Cat', color: 'black', declawed: true })
+    end
+
+    # passes on master too: guards that a subclass narrowing attribute_map is not handed its parent's attributes
+    it 'a subclass that narrows attribute_map is only handed the attributes it accepts' do
+      narrowed = Class.new(Petstore::Animal) do
+        def self.attribute_map
+          { :class_name => :className }
+        end
+
+        def self.openapi_types
+          { :class_name => :'String' }
+        end
+      end
+
+      obj = narrowed.build_from_hash({ 'className' => 'Cat', 'color' => 'black' })
+
+      expect(obj.class_name).to eq('Cat')
+      expect(obj.to_hash).to eq({ className: 'Cat' })
+    end
+  end
 end
diff --git a/samples/openapi3/client/features/generate-alias-as-model/ruby-client/lib/petstore/models/array_alias.rb b/samples/openapi3/client/features/generate-alias-as-model/ruby-client/lib/petstore/models/array_alias.rb
index 9ffe5b9100b1..857c8a4b76da 100644
--- a/samples/openapi3/client/features/generate-alias-as-model/ruby-client/lib/petstore/models/array_alias.rb
+++ b/samples/openapi3/client/features/generate-alias-as-model/ruby-client/lib/petstore/models/array_alias.rb
@@ -21,12 +21,12 @@ def self.attribute_map
       }
     end
 
-    # Returns attribute mapping this model knows about, including the ones defined in its parent(s)
+    # Returns attribute mapping this model knows about
     def self.acceptable_attribute_map
-      superclass.acceptable_attribute_map.merge(attribute_map)
+      attribute_map
     end
 
-    # Returns all the JSON keys this model knows about, including the ones defined in its parent(s)
+    # Returns all the JSON keys this model knows about
     def self.acceptable_attributes
       acceptable_attribute_map.values
     end
@@ -43,6 +43,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -58,9 +68,6 @@ def initialize(attributes = {})
         end
         h[k.to_sym] = v
       }
-
-      # call parent's initialize
-      super(attributes)
     end
 
     # Show invalid properties with the reasons. Usually used together with valid?
@@ -102,20 +109,21 @@ def hash
     # @return [Object] Returns the model itself
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
-      super(attributes)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -124,11 +132,12 @@ def self.build_from_hash(attributes)
     # Returns the object in the form of hash
     # @return [Hash] Returns the object in the form of hash
     def to_hash
-      hash = super
-      self.class.attribute_map.each_pair do |attr, param|
+      hash = {}
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end
 
diff --git a/samples/openapi3/client/features/generate-alias-as-model/ruby-client/lib/petstore/models/map_alias.rb b/samples/openapi3/client/features/generate-alias-as-model/ruby-client/lib/petstore/models/map_alias.rb
index 431c5fbcab6c..78aa109d56b0 100644
--- a/samples/openapi3/client/features/generate-alias-as-model/ruby-client/lib/petstore/models/map_alias.rb
+++ b/samples/openapi3/client/features/generate-alias-as-model/ruby-client/lib/petstore/models/map_alias.rb
@@ -43,6 +43,16 @@ def self.openapi_nullable
       ])
     end
 
+    # Returns attribute type mapping
+    def self.acceptable_openapi_types
+      openapi_types
+    end
+
+    # Returns the nullable attributes
+    def self.acceptable_openapi_nullable
+      openapi_nullable
+    end
+
     # Initializes the object
     # @param [Hash] attributes Model attributes in the form of hash
     def initialize(attributes = {})
@@ -100,18 +110,20 @@ def hash
     def self.build_from_hash(attributes)
       return nil unless attributes.is_a?(Hash)
       attributes = attributes.transform_keys(&:to_sym)
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      map = acceptable_attribute_map
       transformed_hash = {}
-      openapi_types.each_pair do |key, type|
-        if attributes.key?(attribute_map[key]) && attributes[attribute_map[key]].nil?
+      acceptable_openapi_types.each_pair do |key, type|
+        if attributes.key?(map[key]) && attributes[map[key]].nil?
           transformed_hash["#{key}"] = nil
         elsif type =~ /\AArray<(.*)>/i
           # check to ensure the input is an array given that the attribute
           # is documented as an array but the input is not
-          if attributes[attribute_map[key]].is_a?(Array)
-            transformed_hash["#{key}"] = attributes[attribute_map[key]].map { |v| _deserialize($1, v) }
+          if attributes[map[key]].is_a?(Array)
+            transformed_hash["#{key}"] = attributes[map[key]].map { |v| _deserialize($1, v) }
           end
-        elsif !attributes[attribute_map[key]].nil?
-          transformed_hash["#{key}"] = _deserialize(type, attributes[attribute_map[key]])
+        elsif !attributes[map[key]].nil?
+          transformed_hash["#{key}"] = _deserialize(type, attributes[map[key]])
         end
       end
       new(transformed_hash)
@@ -121,10 +133,11 @@ def self.build_from_hash(attributes)
     # @return [Hash] Returns the object in the form of hash
     def to_hash
       hash = {}
-      self.class.attribute_map.each_pair do |attr, param|
+      # include attributes inherited from allOf parents (the nearest declaration wins)
+      self.class.acceptable_attribute_map.each_pair do |attr, param|
         value = self.send(attr)
         if value.nil?
-          is_nullable = self.class.openapi_nullable.include?(attr)
+          is_nullable = self.class.acceptable_openapi_nullable.include?(attr)
           next if !is_nullable || (is_nullable && !instance_variable_defined?(:"@#{attr}"))
         end