Duplicate classes / Models are generated if ( $ref) referenced externally.

Description

If Schemas are referenced in cyclic manner, the Models are generated twice. In below code,the Model ProblemDetails is generated twice as

• ProblemDetails.java
• ProblemDetails2.java

Is the correct way to reference? If Not why? and How to fix the above case?

openapi-generator version

openapi-generator-cli-4.0.0-beta3

OpenAPI declaration file content or url

openapi.yaml

openapi: 3.0.0
info:
  title: Common Data Types
  version: "1.0"
paths:
  /{appId}/subscriptions:
    get:
      summary: read all of the active subscriptions for the app.
      operationId: getSubscriptionsById
      parameters:
        - name: appId
          in: path
          description: App ID
          required: true
          schema:
            type: integer
            format: int64
      responses:
        '200':
          description: OK (Successful)
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Subscription'
        '500':
          $ref: './common.yaml#/components/responses/E500'  
components:
  schemas:
      ProblemDetails:
        type: object
        properties:
          title:
            type: string
            description: A short, human-readable summary of the problem
          status:
            type: integer
            description: The HTTP status code for this occurrence of the problem.
      Subscription:
        type: string

common.yaml

openapi: 3.0.0
info:
  title: Common Data Types
  version: "1.0"
paths: {}
components:
  responses:
    E500:
      description: Server Error
      content:
        application/json:
          schema:
            $ref: './openapi.yaml#/components/schemas/ProblemDetails'

Command line used for generation

java -jar openapi-generator-cli-4.0.0-beta3.jar generate -i openapi.yaml -g spring -o ./temp

Reproduce the report with openapi.yaml and common.yaml using the listed spring generator command. Start by tracing how the external cyclic $ref to ProblemDetails is resolved and how model names are assigned. Done means the sample generates one ProblemDetails.java rather than a second suffixed model, with regression coverage for the two-file reference cycle.