title: OpenAPI models not being generated when using oneOf
body: <p>I am using OpenAPI+OpenAPI-generator with spring boot, and trying to use the schema <code>oneof</code> as follows:</p>
  <p>This is the configuration in the requests.yaml file:</p>
  <pre><code>...
  
  requestBody:
   name: request
   required: true
   content:
     application/json:
       schema:
         oneOf:
           - $ref: 'components.yaml#/Request'
           - $ref: 'components.yaml#/ComplexRequest'
  
  ...
  </code></pre>
  <p>and this is the relevant configuration in the components.yaml file:</p>
  <pre><code>Request:
    allOf:
      - $ref: '#/BaseInfo'
      - type: object
        properties:
          should_create:
            type: boolean
            enum: [ false ]
          reference_id:
            type: string
          required:
            - reference_id
  
  ComplexRequest:
    allOf:
      - $ref: '#/BaseInfo'
      - type: object
        properties:
          should_create:
            type: boolean
            enum: [ true ]
          create_data:
            $ref: '#/Reference'
        required:
          - create_data
  
  BaseInfo:
    type: object
    properties:
      customer_id:
        type: string
  
  Reference:
    type: object
    properties:
      propery_1:
        type: string
      propery_2:
        type: string
      propery_3:
        type: string
  </code></pre>
  <p>For some reason, all of these components and only these are not being generated.
  Can someone enlighten me on what am I doing wrong here?</p>