protected function create_folder()
    {
        $fileMetadata = new \Google_Service_Drive_DriveFile([
            'name'     => 'google_drive_folder_name',
            'mimeType' => 'application/vnd.google-apps.folder',
        ]);

        $folder = $this->service->files->create($fileMetadata, ['fields' => 'id']);

        return $folder->id;
    }