{
  "properties": {
    "a": {
      "$ref": "#/definitions/common",
      "description": "Description of a",
      "default": "Default from a"
     } ,
    "b": {
      "$ref": "#/definitions/common",
      "default": "Default from b"
     }
  },
  "definitions": {
    "common": {
      "description": "A common description"
    }
  }
}