[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).

Run the provided Java generator commands against polymorphy.yaml and compare the generated Cat.java files from versions 4.3.0 and 4.3.1. Trace the Java generator behavior responsible for model inheritance; done means the 4.3.1 output restores Cat extending PetBase, as in 4.3.0.