public function withFile($key, $path, $mimeType = '', $postFileName = '')
    {
        $fileData = array(
            'fileName'     => $path,
            'mimeType'     => $mimeType,
            'postFileName' => $postFileName,
        );

        $this->packageOptions[ 'files' ][ $key ] = $fileData;

        return $this->containsFile();
    }