JsonSubTypes.Type bad class name

swagger: "2.0"
info:
  version: "1.0.0"
  title: "Swagger Petstore"
basePath: "/v2"
consumes:
- "application/json"
produces:
- "application/xml"
paths:
  /pet:
    get:
      responses:
        400:
          description: "Invalid input"
          schema:
            $ref: "#/definitions/error"
definitions:
  invalid-foo-error:
    allOf:
      - $ref: '#/definitions/error'
      - type: object
        required:
          - key
          - foo
        properties:
          key:
            type: string
            default: invalid-time-bounds-error
            readOnly: true
          message:
            type: string
          foo:
            type: string
  error:
    type: object
    discriminator: key
    required:
      - key
    properties:
      key:
        type: string
        default: generic-error
      message:
        type: string