x-discriminator reproduction case

defs.yml

Transaction:
  type: object
  properties:
    id:
      type: string
      example: A11234
      pattern: '[A-Z][0-9]{1,32}'
      readOnly: true
    account_id:
      type: string
      example: 05a2106b-92a4-4ee3-a6a3-c32f8b609de1
      format: uuid
      readOnly: true
    operation_type:
      type: string
      enum:
        - payment
        - refund
      example: payment
    payment_method:
      $ref: '#/PaymentMethod'

PaymentMethod:
  type: object
  x-discriminator:
    propertyName: type
    mapping:
      visa: "#/paymentMethodVisa"
      mastercard: "#/paymentMethodMastercard"
      amex: "#/paymentMethodAmex"
  properties:
    type:
      description: The type of Payment Method used for Transaction
      type: string

paymentMethodVisa:
  description: A visa
  allOf:
    - $ref: '#/PaymentMethod'
    - properties:
        prop1:
          type: string
          description: A custom prop
          enum:
            - type1
            - type2
    - properties:
        type:
          type: string
          enum:
            - visa

paymentMethodMastercard:
  description: A mastercard
  allOf:
    - $ref: '#/PaymentMethod'
    - properties:
        prop1:
          type: string
          description: A custom prop
          enum:
            - type3
            - type4
    - properties:
        type:
          type: string
          enum:
            - mastercard
paymentMethodAmex:
  description: A amex
  allOf:
    - $ref: '#/PaymentMethod'
    - properties:
        prop1:
          type: string
          description: A custom prop
          enum:
            - type5
    - properties:
        type:
          type: string
          enum:
            - amex

swagger.yml

swagger: '2.0'
info:
  version: 1.0.0
  title: Test API

host: test.api.int.com
basePath: /v2
schemes:
  - https
securityDefinitions:
  basic:
    type: basic
consumes:
  - application/json
produces:
  - application/json

paths:
  '/transactions/{id}':
    get:
      summary: Get a transaction by ID
      description: Get a `Transaction` object by ID
      parameters:
        - name: id
          in: path
          description: The transaction ID
          required: true
          type: string
          format: uuid
      responses:
        '200':
          description: The Transaction
          schema:
            $ref: 'defs.yml#/Transaction'

parameters: