code: protected static function getMessage(/*# int */ $code)/*# : string */
      {
          $mapping = static::getMappings();
          if (isset($mapping[$code])) {
              return $mapping[$code];
          }
          return (string) $code;
      }
docs: Resolving code for current message class, from cache or default
  
  If nothing found, return the code anyway
  
  @param  int $code the message code
  @return string
  @access protected