#24174 [java][jaxrs-spec][quarkus] - Add support for OneOfInterfaces & fix JsonTypeName value resolution

Add support for OneOfInterfaces to avoid having circular dependencies because the child schemas components extend a parent class that also has oneOf and mapping pointing to the children.

The bug

x-discriminator-value was only ever populated from a model's Java parentModel. That works for classic allOf inheritance (CatRequest extends PetRequest), but not for the useOneOfInterfaces shape: there the child allOfs a shared base that gets flattened, so the child has no parentModel — it only implements the generated interface, and the discriminator lives on that interface, not on any Java parent.

Result: for oneOf-interface children, x-discriminator-value was never set, and @JsonTypeName fell back to the class name:

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "petType", visible = true)
@JsonSubTypes({
  @JsonSubTypes.Type(value = CatRequest.class, name = "CAT"),
  @JsonSubTypes.Type(value = DogRequest.class, name = "DOG"),
})
public interface PetRequest { PetType getPetType(); }

// Before — wrong: class name, not the mapping value
@JsonTypeName("CatRequest")
public class CatRequest implements PetRequest { … }

// After — correct: the discriminator mapping value
@JsonTypeName("CAT")
public class CatRequest implements PetRequest { … }

Example:

   # -----------------------------------------------
   # Base schema in component that contains oneOf and mapping
   # Discriminator also lives here on the parent
   # Child classes have a circular dependency because allOf to the parent with the oneOf & mapping
   # PetRequest (mapping) -> CatRequest (allOf) -> PetRequest
   # -----------------------------------------------

   PetRequest:
     type: object
     required:
       - petType
       - name
     properties:
       petType:
         type: string
         enum:
           - CAT
           - DOG
       name:
         type: string
     discriminator:
       propertyName: petType
       mapping:
         CAT: '#/components/schemas/CatRequest'
         DOG: '#/components/schemas/DogRequest'

   CatRequest:
     type: object
     allOf:
       - $ref: '#/components/schemas/PetRequest'
       - type: object
         required:
           - breedType
           - petType
         properties:
           breedType:
             $ref: '#/components/schemas/CatBreedType'
   DogRequest:
     type: object
     allOf:
       - $ref: '#/components/schemas/PetRequest'
       - type: object
         properties:
           breedType:
             $ref: '#/components/schemas/DogBreedType'


   # -----------------------------------------------
   # Base schema a separate component
   # Discriminator lives in parent and base object until #24156 is merged
   # -----------------------------------------------

   PetRequestV2:
     type: object
     properties:
       petType:
         $ref: '#/components/schemas/PetType'      # --> This will removed once #24156 is merged
     oneOf:
       - $ref: '#/components/schemas/CatRequestV2'
       - $ref: '#/components/schemas/DogRequestV2'
     discriminator:
       propertyName: petType
       mapping:
         CAT: '#/components/schemas/CatRequestV2'
         DOG: '#/components/schemas/DogRequestV2'

   PetRequestV2Base:
       type: object
       required:
         - petType
         - name
       properties:
         petType:
           $ref: '#/components/schemas/PetType'
         name:
           type: string
   
   CatRequestV2:
     type: object
     allOf:
       - $ref: '#/components/schemas/PetRequestV2Base'
       - type: object
         properties:
           breedType:
             $ref: '#/components/schemas/CatBreedType'
          

   DogRequestV2:
     type: object
     allOf:
       - $ref: '#/components/schemas/PetRequestV2Base'
       - type: object
         properties:
           breedType:
             $ref: '#/components/schemas/DogBreedType'

PR checklist

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Summary by cubic

Adds useOneOfInterfaces to jaxrs-spec, generating oneOf schemas as Java interfaces with a typed discriminator getter, and fixes subtype mapping so @JsonTypeName uses the discriminator mapping value. Opt-in; default output is unchanged.

• New Features

  • Route x-is-one-of-interface models in model.mustache to oneof_interface.mustache to emit a plain interface with Jackson type info and a typed getter (enum when applicable); supports additionalOneOfTypeAnnotations.mustache and optional JsonTypeInfo.DEDUCTION.
  • Add sample samples/server/petstore/jaxrs-spec-oneof-interface, config bin/configs/jaxrs-spec-oneof-interface.yaml, tests, and register the sample in the JAX-RS samples workflow.

• Bug Fixes

  • In JavaJAXRSSpecServerCodegen, index discriminators for generated oneOf interfaces and resolve subtype mappings from either parentModel or the implemented interface via x-implements, setting x-discriminator-value for correct @JsonTypeName and Jackson polymorphic (de)serialization.