[BUG] [java] Polymorphy of models broken in v4.3.1

Description

Using the java generator, I used to get models where child-classes extend parent classes with version 4.3.0. With version 4.3.1 the child classes do not extend the parent class anymore.

openapi-generator version

It’s a regression of version 4.3.1. 4.3.0 worked.

OpenAPI declaration file content or url

openapi: "3.0.0"
info:
    version: 1.0.0
    title: Polymorphy demo
paths:
    /random-pet:
        get:
            responses:
                '200':
                    description: Returning a random pet.
                    content:
                        application/json:
                            schema:
                                $ref: "#/components/schemas/Pet"
components:
    schemas:
        Pet:
            oneOf: 
                - $ref: '#/components/schemas/Dog' 
                - $ref: '#/components/schemas/Cat' 
            discriminator: 
                propertyName: petType
                mapping: 
                    dog: '#/components/schemas/Dog' 
                    cat: '#/components/schemas/Cat' 
        PetBase:
            type: object
            required:
                - petType
            properties:
                petType:
                    type: string
                name:
                    type: string
        Dog:
            allOf:
                - $ref: '#/components/schemas/PetBase'
                - type: object
                  properties:
                      barksAlot:
                          type: boolean
        Cat:
            allOf:
                - $ref: '#/components/schemas/PetBase'
                - type: object
                  properties:
                      goesOutdoors:
                          type: boolean

Generation Details

I run the generator in version 4.3.0 and 4.3.1:

$ java -jar openapi-generator-cli-4.3.0.jar generate -g java -o 4.3.0_result -i polymorphy.yaml
$ java -jar openapi-generator-cli-4.3.1.jar generate -g java -o 4.3.1_result -i polymorphy.yaml

Steps to reproduce

After generating the code in 4.3.0 and 4.3.1, compare Cat.java. The generated model of 4.3.0 will contain public class Cat extends PetBase while the generated model of 4.3.1 will only contain public class Cat (without the inheritance).

[marcdejonge]

Ok, an update. In 4.3.1 it added support for the discriminator. After playing around I got the expected result for me by changing the models as follows:

openapi: "3.0.0"
info:
  version: 1.0.0
  title: Polymorphy demo
paths:
  /random-pet:
    get:
      responses:
        '200':
          description: Returning a random pet.
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/Pet"
components:
  schemas:
    Pet:
      type: object
      required:
        - petType
      properties:
        petType:
          type: string
        name:
          type: string
      discriminator:
        propertyName: petType
        mapping:
          dog: '#/components/schemas/Dog'
          cat: '#/components/schemas/Cat'
    Dog:
      allOf:
        - $ref: '#/components/schemas/Pet'
        - type: object
          properties:
            barksAlot:
              type: boolean
    Cat:
      allOf:
        - $ref: '#/components/schemas/Pet'
        - type: object
          properties:
            goesOutdoors:
              type: boolean

[epabst]

After I got the Pet model working that @marcdejonge provided in https://github.com/OpenAPITools/openapi-generator/issues/9615#issuecomment-861304768, I figured out a workaround for my own issue. I had separate yaml files for my schema model classes, and by moving them into the same file as the endpoints under this, it worked for me!!!

components:
  schemas:

Note, I also applied this fix to avoid the extra AllOf classes: https://github.com/OpenAPITools/openapi-generator/issues/3100#issuecomment-703481081