def from_json(json, mapper = nil)
      mapper = self.class.mapper if mapper.nil?
      deserialize(mapper, json)
    end
def from_json(json, mapper = nil)
      mapper = self.class.mapper if mapper.nil?
      deserialize(mapper, json)
    end
Deserialize the object from JSON
 @param json [String] JSON string representation of the object
 @return [JSONable] object built from json input