protected function parseDateFromFilename($filename)
    {
        if ($date = \DateTime::createFromFormat(self::FILE_NAME_PATTERN, explode('_', $filename)[0])) {
            return $date;
        }

        /**
         * @deprecated handle BC break of PR #62. will be remove in 1.0-RC1.
         */
        return \DateTime::createFromFormat('H-i-s-Y-m-d', explode('_', $filename)[0]);
    }