[BUG] Java generator does not generate oneOf interface

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?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
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Description

the java generator on openapi-generator-maven-plugin 5.4.0 doesn't compile with an openapi which contain an oneOf instructions.
The interfaces OneOf are not generated.

Compilation failure: Compilation failure:
[ERROR] /Users/XXX/git/service/contract/target/generated-sources/openapi/src/main/java/blabla/model/Person.java:[48,23] error: cannot find symbol
[ERROR]   symbol:   class OneOfCatDog
[ERROR]   location: class Person

I tried with previous versions and the only one which compile is the 4.3.1.
Unfortunately the generated interface contain an empty JsonSubTypes annotation : the mapper cannot map correctly the object

@javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", date = "2022-02-25T12:39:36.701392+01:00[Europe/Paris]")
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.EXISTING_PROPERTY, property = "pet_type", visible = true)
@JsonSubTypes({
})

public interface PersonPetOneOf  {
    public String getPetType();
}

openapi-generator version

version : 5.4.0

OpenAPI declaration file content or url

openapi: "3.0.3"
info:
  title: "notification"
  version: "1.0"
tags:
  - name: notify
servers:
  - url: /person
paths:
  /person:
    post:
      security:
        - basicAuth: []  
      tags:
        - notify
      operationId: aaa
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/Person'
      responses:
        '200':
          description : "retour ok"
         
components:
  securitySchemes:
    basicAuth:    
      type: http
      scheme: basic
  schemas:
    Pet:
      type: object
      required:
        - pet_type
      properties:
        pet_type:
          type: string
      discriminator:
        propertyName: pet_type
    Dog:    
      allOf:  
        - $ref: '#/components/schemas/Pet'
        - type: object
          properties:
            bark:
              type: boolean
            breed:
              type: string
              enum: [Dingo, Husky, Retriever, Shepherd]
    Cat:     
      allOf: 
        - $ref: '#/components/schemas/Pet'
        - type: object
          # all other properties specific to a `Cat`
          properties:
            hunts:
              type: boolean
            age:
              type: integer
    Person:
      properties:
        name:
          type : string
        pet:
          oneOf:
             - $ref: '#/components/schemas/Cat'
             - $ref: '#/components/schemas/Dog'
          discriminator:
            propertyName: pet_type

Generation Details

java : version 11
maven : version 3.5.3
pom.xml

<plugin>
	<groupId>org.openapitools</groupId>
	<artifactId>openapi-generator-maven-plugin</artifactId>
	<version>5.4.0</version>
	<!-- <version>4.3.1</version> -->
	<executions>
		<execution>
			<goals>
				<goal>generate</goal>
			</goals>
			<configuration>
				<inputSpec>${project.basedir}/src/main/resources/static/openapi/notifier-v1.yaml</inputSpec>
				<generatorName>java</generatorName>
				<apiPackage>blabla.api</apiPackage>
				<modelPackage>blabla.model</modelPackage>
				<library>resttemplate</library>
				<configOptions>
					<generateModels>true</generateModels>
					<dateLibrary>java8</dateLibrary>
				</configOptions>
			</configuration>
		</execution>
	</executions>
</plugin>

Steps to reproduce

mvn clean install

Related issues/PRs

Suggest a fix

The java generator should generate the OneOf Interface and the JsonSubTypes annotation should contains the object mapping.

Start with the pom.xml configuration and supplied OpenAPI declaration, then run mvn clean install to reproduce the generated-source failure. Inspect target/generated-sources/openapi/src/main/java/blabla/model/Person.java and the generated PersonPetOneOf interface. Done means the Java generator produces the interface, includes the object mappings in JsonSubTypes, and the generated project compiles.