[JAVA] Problem with duplicate schema names when using external references

Created by: emreakca

Description

The external reference from child to ../openapi.yaml#/components/schemas/Parent doesn't resolve correctly. It creates a empty Parent2.java class and references to Parent2. The code works just fine with the Swagger UI and parsing/validating is also not a problem.

openapi-generator version

3.1.0 / 4.0.x

OpenAPI declaration file content or url

openapi.yaml

components:
  schemas:
    Parent:
      $ref: './components/parent.yaml#/Parent'
    Child:
      $ref: './components/child.yaml#/Child'

parent.yaml

Parent:
  title: parent
  type: object
  properties:
    id:
      type: string
      description: ID of the resource

child.yaml

Child:
  title: Child
  allOf:
  - $ref: '../openapi.yaml#/components/schemas/Parent'
  type: object
  properties:
    name:
      type: string
      description: Name of the child

Complete Upload --> https://gist.github.com/emreakca/7291275cfba475d3f6384b92cdfb4554

Command line used for generation

java -jar modules/openapi-generator-cli/target/openapi-generator-cli.jar generate -i ./openapi.yaml -g java -o ./out/java-family-api

Steps to reproduce

Generate client.

Suggest a fix/enhancement

The openapi-generator should generate the code correctly.