protected function listDirectoryContents($directory = '.')
    {
        if ($directory && strpos($directory, '.') !== 0) {
            ftp_chdir($this->getConnection(), $directory);
        }

        $listing = @ftp_rawlist($this->getConnection(), '.') ?: [];

        $this->setConnectionRoot();

        return  $this->normalizeDirectoryListing($listing);
    }