[QoS Booking And Assignment] 409 INCOMPATIBLE_STATE example message does not fit the API #175

Problem description

The 409 responses DeleteBooking409 and DeviceAssignment409 reference the shared example GENERIC_409_INCOMPATIBLE_STATE from CAMARA_common.yaml (L1337, L1362). Its message reads "Resource must be in AVAILABLE state to extend. Current state is UNAVAILABLE.", which describes a session extension and names states this API does not have. In the bundled release artefact this is the text an implementer sees for a booking that cannot be deleted or cannot take devices.

The shared example itself is reported in camaraproject/Commonalities#734.

Expected behavior

Until the common example is corrected, define a local example with a message that fits this API, for instance "The booking is in a state that does not allow the requested operation.", and reference it from both 409 responses. Switch back to the common example once Commonalities#734 is resolved and adopted.

Alternative solution

Wait for the Commonalities fix and the next dependency bump.

Additional context

Found in the review of release r2.2 snapshot #160. qos-booking is not affected; it declares no INCOMPATIBLE_STATE response.