[BUG][jaxrs-spec] Discriminated model serializes a duplicate `type` with the class name instead of the discriminator value

[jaydeep-punjani]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?

Description

For a discriminated polymorphic model (oneOf-by-inheritance via allOf + discriminator.mapping), the jaxrs-spec generator produces Java that serializes a duplicate discriminator property with the wrong value.

The generated base class is annotated:

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "type", visible = true)

and each concrete subtype gets:

@JsonTypeName("TrackMessage")   // <-- the CLASS NAME, not the discriminator value "track"

Because visible = true keeps type as a real bean property and the type id is emitted from @JsonTypeName (the class name), serializing a subtype yields a duplicate key:

{"type":"TrackMessage","type":"track", ...}

Deserialization is correct (it uses the @JsonSubTypes name = "track" mapping); only serialization is broken.

This is not fixable from the spec: x-discriminator-value (at the child schema top level or inside the allOf member), removing the type property, and removing the discriminator mapping all fail to change @JsonTypeName/visible. Removing the mapping additionally breaks reads (@JsonSubTypes then uses the class name).

openapi-generator version

Reproduced on 7.7.0, 7.11.0, and 7.14.0 (identical output).

OpenAPI declaration file content or url

openapi: 3.1.0
info: { title: repro, version: 1.0.0 }
paths: {}
components:
  schemas:
    MessageType:
      type: string
      enum: [track, page]
    AnyMessage:
      type: object
      required: [type]
      properties:
        type: { $ref: '#/components/schemas/MessageType' }
        messageId: { type: string }
      discriminator:
        propertyName: type
        mapping:
          track: '#/components/schemas/TrackMessage'
          page: '#/components/schemas/PageMessage'
    TrackMessage:
      allOf:
        - $ref: '#/components/schemas/AnyMessage'
        - type: object
          required: [event]
          properties:
            event: { type: string }
    PageMessage:
      allOf:
        - $ref: '#/components/schemas/AnyMessage'
        - type: object
          properties:
            name: { type: string }

Generation command

openapi-generator-cli generate -g jaxrs-spec -i repro.yaml -o out \
  -p interfaceOnly=true,useJakartaEe=true,useBeanValidation=true,dateLibrary=java8

Steps to reproduce

1. Generate with the command above.
2. Inspect AnyMessage.java → @JsonTypeInfo(..., property = "type", visible = true).
3. Inspect TrackMessage.java → @JsonTypeName("TrackMessage") (class name, not track).
4. new ObjectMapper().writeValueAsString(trackMessage) → {"type":"TrackMessage","type":"track", ...}.

Expected

Serializing a TrackMessage should emit a single, correct discriminator: {"type":"track", ...}. @JsonTypeName should be the discriminator value from the mapping (track), and the generator should not emit type twice (either visible = false, or suppress the redundant bean property on write).

Related issues/PRs

Searched open issues; none found matching this jaxrs-spec discriminator-serialization case.

Suggested fix

Either set @JsonTypeName to the discriminator value derived from discriminator.mapping (currently the schema/class name), or avoid double-emitting the discriminator when visible = true and a same-named bean property exists.

[jpfinne]

@jaydeep-punjani 7.14.0 is very old.

Testing on the 7.24.0.SNAPSHOT, I get

@JsonTypeName("track")
public class TrackMessage extends AnyMessage  {

Can you retest with 7.23.0 or above?

[Ignacio-Vidal]

I contributed 2 fixes for the jaxrs-spec, recently. You shouldn't get the bug with the 7.24.0.SNAPSHOT

• Add JsonIgnoreProperties to avoid the duplicated key in the serialisation - [jaxrs-spec] Add @JsonIgnoreProperties on the discriminator to avoid duplicated keys during serialisation  #24132
• Resolve the JsonTypeInfo from the mapping correctly - [java][jaxrs-spec][quarkus] - Add support for OneOfInterfaces & fix JsonTypeName value resolution #24174