Parser is not resolving enum in reference discriminator

[gracekarina]

related to #927
Model Product discriminator field productType is referenced to $ref: '#/definitions/ProductType'. which contains the enum which will be extending this model.

In this case extended model does not come in resolved YAML.

swagger: '2.0'
info:
  version: '1.0'
  title: 'Product Operation'
  description: 'Product Operation'


basePath: /commerce

consumes:
  - application/json
produces:
  - application/json

paths:

  /v1/product/{productId}:
    get:
      summary: Get the product
      description: Get the product
      parameters:
        - name: productId
          in: path
          required: true
          type: string
      responses:
        200:
          description: OK
          schema:
            $ref: 'commonDefinitionDomain.yaml#/definitions/Product'
        400:
          $ref: 'commonDefinitionDomain.yaml#/responses/400-BadRequest'

info:
  description: "This is a common Domain"
  version: "1.0"
  title: Common Domain

responses:

  400-BadRequest:
    x-dox-Since: v10.2
    description: Bad Request
    schema:
      $ref: "#/definitions/ErrorResponse"

definitions:
  ErrorResponse:
    x-dox-Since: v10.2
    type: object
    description: |
      Response containing descriptive error text, error code
    required:
    - code
    - message
    properties:
        code:
          description: |
            The code associated with the error
          readOnly: true
          type: integer
        message:
          description: |
            The message associated with the error
          readOnly: true
          type: string

  ChannelType:
    type: string
    enum:
      - selfService
      - retail
      - callCenter
      
  Product:
    x-dox-Since: '10.2'
    description: |
      The respresentation of the product
    type: object
    discriminator: productType
    required: 
      - productType
    x-dox-discriminator-name: NAME
    x-dox-discriminator-type:
      - MobileProduct
      - InternetProduct
      - FixedVoiceProduct
    properties:
      id:
        type: string
      status:
        type: string
      name:
        type: string
      productType:
        $ref: '#/definitions/ProductType'
    
  ProductType:
    x-dox-Since: '10.2'
    description: |
      The different type of products
    enum:
      - MobileProduct
      - FixedVoiceProduct
      - InternetProduct

  MobileProduct:
    x-dox-Since: 10.2
    description: |
      The instance of the mobile product being added.
    type: object
    allOf:
      - $ref: "#/definitions/Product"
      - type: object
        properties:
          sim:
            type: string
          phoneNumber:
            type: string

  FixedVoiceProduct:
    x-dox-Since: 10.2
    description: |
      The instance of the fixed voice product being added.
    type: object
    allOf:
      - $ref: "#/definitions/Product"
      - type: object
        properties:
          phoneNumber:
            type: string

  InternetProduct:
    x-dox-Since: 10.2
    description: |
      The instance of the internet product being added.
    type: object
    allOf:
      - $ref: "#/definitions/Product"
      - type: object
        properties:
          userName:
            type: string
          speed:
            type: string

[gracekarina]

closed by #1004