allOf validation not working? #120

openapi: 3.0.0
info:
  title: AllOf.v1
  version: '1.0'
servers:
  - url: 'http://localhost:3000'
paths:
  /pets:
    patch:
      requestBody:
        content:
          application/json:
            schema:
              oneOf:
                - $ref: '#/components/schemas/Cat'
                - $ref: '#/components/schemas/Dog'
              discriminator:
                propertyName: pet_type
      responses:
        '200':
          description: Updated
components:
  schemas:
    Pet:
      type: object
      required:
        - pet_type
      properties:
        pet_type:
          type: string
    Dog: # "Dog" is a value for the pet_type property (the discriminator value)
      allOf: # Combines the main `Pet` schema with `Dog`-specific properties
        - $ref: '#/components/schemas/Pet'
        - type: object
          # all other properties specific to a `Dog`
          properties:
            bark:
              type: boolean
            breed:
              type: string
              enum: [ Dingo, Husky, Retriever, Shepherd ]
    Cat: # "Cat" is a value for the pet_type property (the discriminator value)
      allOf: # Combines the main `Pet` schema with `Cat`-specific properties
        - $ref: '#/components/schemas/Pet'
        - type: object
          # all other properties specific to a `Cat`
          properties:
            hunts:
              type: boolean
            age:
              type: integer