public function addFiles($files, $type = '', $locale = null, $keepOriginal = false): void
    {
        $files  = (array) $files;
        $locale = $this->normalizeLocaleString($locale);

        if (is_string(array_values($files)[0])) {
            foreach ($files as $filename => $file) {
                $this->addFile($file, $type, $locale, $filename, $keepOriginal);
            }
        } else {
            foreach ($files as $filename => $file) {
                $this->addFile($file, $type, $locale, $filename, $keepOriginal);
            }
        }
    }