fix: Read class-level prefixes of composed controller annotations as Spring merges them (#672)

[imuromtsev]

Purpose

A controller annotated with a composed annotation such as

@Target(TYPE) @Retention(RUNTIME)
@RestController
@RequestMapping
@interface ApiController {
    @AliasFor(annotation = RequestMapping.class, attribute = "path")
    String[] path() default "/api";
}

is served by Spring under /api/..., but the plugin read the class-level prefix from the values written at the use site only, so @ApiController class ItemsController lost its prefix in the endpoint model and in every consumer of the class prefix. #673 added the merged-values resolver; this PR switches the class-level prefix to it. First caller group of #672.

Change

• HandlerMethods.requestMappingPrefixes reads the class mapping through the merged UAST API (MetaAnnotationsHolder / MergedAnnotationAttributes from fix: Read composed annotations as Spring merges them (#651) #673): @AliasFor defaults and use-site values, an alias to value, a second composed level, a meta-fixed path. An unaliased attribute named like a mapping path attribute (convention mapping) sets the prefix only when the Spring major is known and below 7, as Spring does; an unknown version applies no convention.
• Spring uses only the first @RequestMapping descriptor of an element, ordered by meta-distance (RequestMappingHandlerMapping.createRequestMappingInfo, "only the first will be used"). The prefix is read from exactly that annotation: a direct @RequestMapping wins over a composed one in any source order; ties go to declaration order. New MetaAnnotationsHolder.nearestAnnotation (+ MergedAnnotationAttributes.metaDistanceOf) implements the rule.
• SpringWebControllerLoader reuses requestMappingPrefixes instead of its own declared-only copy. When a class cannot be converted to UAST, the declared PSI values of the nearest annotation are read as before.
• Consumers that now get the merged prefix: the Endpoints tool window and Spring MCP endpoint tools (loader), the controller/endpoint run gutters and "Generate OpenApi Specification".

Framework evidence

Probe on real jars (spring-webmvc / spring-webflux 6.2.19 and 7.0.9), prefix registered for each case:

Case	6.2.19	7.0.9
alias to path, default /api, bare	/api	/api
alias, use-site /v2	/v2	/v2
two values	/x, /y	/x, /y
alias to value, default /dval	/dval	/dval
meta-fixed @RequestMapping("/fixed")	/fixed	/fixed
two composed levels	/api	/api
unaliased same-named path (convention)	/conv	no prefix

Not in this PR (remaining #672 groups)

• Method-level @RequestMapping readers still on the declared PSI overload (gutters, OpenAPI endpoint info, duplicate mapping inspection), and SpringWebUtil.requestMappingOf, which merges values of every mapping annotation of a handler method instead of the nearest one.
• @HttpExchange loader, @ConditionalOnBean/@ConditionalOnMissingBean, PropertyConditionSpecReader, OnWebApplicationCondition.

Verification

• Red commits 721dc27 (9 reds: alias default, alias to value, two levels, convention on Spring 6, HandlerMethods; Java and Kotlin) and e716b94 (8 reds: a direct @RequestMapping beside a composed one, both source orders, loader and HandlerMethods, Java and Kotlin).
• After the fixes: ComposedMappingDefaultPathTest 15/15, ComposedControllerPrefixSpring7Test 2/2, Kotlin ComposedControllerPrefixTest 10/10; gutter, OpenAPI and loader suites 184/184; MetaAnnotationsHolderMergedValues* 45/45.
• All modules (:spring-bootstrap:test --rerun-tasks on 7d44c43, fresh JUnit XML): spring-core 2387, spring-web 930 (6 skipped), spring-ai 776, jpa 138, spring-data 140, base 35, aop 6, security 6, initializr 5 — 0 failures except one spring-ai ThreadLeakTracker leak assertion in SpringBootApplicationMcpToolsetOutsideProjectRootTest, which passed 4/4 when rerun alone (known flake).

Main only: MergedAnnotationAttributes (#673) is not on the release branches.

Refs #672

[github-actions]

	Tests	Passed ✅	Skipped ⚠️	Failed
JUnit Test Report	4423 ran	4417 passed	6 skipped	0 failed

• View JUnit Test Report