OpenApi Polymorphism

openapi.yaml

openapi: 3.0.2
info:
  title: OAI Specification example for Polymorphism
  version: 1.0.0
paths:
  /pet:
    get:
      responses:
        '200':
          description: desc
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Pet'
  /reptile:
    get:
      responses:
        '200':
          description: desc
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Reptile'
  /mypets:
    get:
      responses:
        '200':
          description: desc
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/MyPets'
components:
  schemas:
    PetBase:
      type: object
      required:
        - petType
      properties:
        petType:
          type: string
    Pet:
      oneOf:
       - $ref: '#/components/schemas/Cat'
       - $ref: '#/components/schemas/Dog'
       - $ref: '#/components/schemas/Reptile'
       - $ref: '#/components/schemas/Lizard'
       - $ref: '#/components/schemas/Snake'
      discriminator:
        propertyName: petType
    CatBase:
      allOf:
        - $ref: '#/components/schemas/PetBase'
        - type: object
          properties:
            name:
              type: string
    Cat:
      allOf:
        - $ref: '#/components/schemas/CatBase'
    ReptileBase:
      allOf:
        - $ref: '#/components/schemas/PetBase'
        - type: object
          properties:
            lungSize: 
              type: number
    Reptile:
      oneOf:
       - $ref: '#/components/schemas/Lizard'
       - $ref: '#/components/schemas/Snake'
       - type: object
         allOf:
          - $ref: '#/components/schemas/ReptileBase'
      discriminator:
        propertyName: petType
    DogBase:
      allOf:
        - $ref: '#/components/schemas/PetBase'
        - type: object
          properties:
            bark:
              type: string
    Dog:
      allOf:
        - $ref: '#/components/schemas/DogBase'
    LizardBase:
      allOf:
        - $ref: '#/components/schemas/ReptileBase'
        - type: object
          properties:
            lovesRocks:
              type: boolean
    Lizard:
      allOf:
        - $ref: '#/components/schemas/LizardBase'
    SnakeBase:
      allOf:
        - $ref: '#/components/schemas/ReptileBase'
        - type: object
          properties:
            hasLegs:
              type: boolean
    Snake:
      allOf:
        - $ref: '#/components/schemas/SnakeBase'
    MyPets:
      oneOf:
        - $ref: '#/components/schemas/Cat'
        - $ref: '#/components/schemas/Lizard'
      discriminator:
        propertyName: petType
        # per https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md#discriminatorObject
        # this discriminator must be included to use it as a hint to pick a schema
    MyPetsNoDisc:
      oneOf:
        - $ref: '#/components/schemas/Cat'
        - $ref: '#/components/schemas/Lizard'