protected function getPlaceHolders(/*# string */ $message)/*# : array */
    {
        // not found
        if (false === strpos($message, '{')) {
            return [];
        }

        $matches = [];
        $pattern = '~\{([^\}]+)\}~';
        if (preg_match_all($pattern, $message, $matches)) {
            return array_combine($matches[1], $matches[0]);
        }
        return [];
    }