code: public static Parameters fromJson(String json) {
  		Map<String, Object> map = JsonConverter.toNullableMap(json);
  		return map != null ? new Parameters(map) : new Parameters();
  	}
docs: Creates new Parameters from JSON object.
  
  @param json a JSON string containing parameters.
  @return a new Parameters object.
  
  @see JsonConverter#toNullableMap(String)