{
  "description" : "Application Data",
  "type":"object",
  "$schema": "http://json-schema.org/draft-03/schema",
  "required":true,
  "properties": {
    "payment": {
      "type":"object",
      "required":true,
      "additionalProperties":false,
      "properties": {
        "amount": {
          "required":true,
          "extends" : "types.json#/amount"
        },
        "other_amount": {
          "required":true,
          "extends" : {"$ref": "types.json#/amount"}
        },
       "usage": {
          "$ref": "types.json#/usage"
        }
      }
    }
  }
}