{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "definitions": {
    "pets": {
      "type": "object",
      "properties": {
        "dog": {
          "type": "string"
        },
        "cat": {
          "type": "string"
        }
      },
      "required": ["dog", "cat"]
    },
    "morePets": {
      "allOf": [
        {
          "$ref": "#/definitions/pets"
        },
        {
          "type": "object",
          "properties": {
            "horse": {
              "type": "string"
            }
          }
        }
      ]
    }
  }
}