code: public static String getValidationError(String code, Object... msgValues) {
          if (!_MESSAGES.containsKey(code))
              throw new RuntimeException("Unknown code: " + code);
          return fillMessage(_MESSAGES.get(code), msgValues);
      }
docs: Returns the error message for the given error code
  @param code error code
  @param msgValues optional values to plug into the message
  @return the corresponding error message, never null (will throw an runtime exception if unknown code)