protected function hashedCombinedFilename($combinedFile, $fileList)
    {
        $name = pathinfo($combinedFile, PATHINFO_FILENAME);
        $hash = $this->hashOfFiles($fileList);
        $extension = File::get_file_extension($combinedFile);
        return $name . '-' . substr($hash, 0, 7) . '.' . $extension;
    }