如何在php中使用google drive api在多个电子邮件地址上共享文件

I want to share a file on multiple email address using google drive api. I have enabled the google drive api and set the credentials over there. I am able to share a file on single email address with below code but i want to share a file on multiple Email address so please tell me how to fix this issue.

$client  = getClient();
$service = new Google_Service_Drive($client);
$fileId = '1cFHdHkVw-9UzBq2N1v4Yaf0UPzBBUuAW'; 
$userPermission = new Google_Service_Drive_Permission(array(
    'type' => 'group',
    'role' => 'writer',
    'emailAddress' => 'navneet4561@gmail.com'
)); 
$request = $service->permissions->create(
    $fileId, $userPermission, array('fields' => 'id'));

if($request instanceof Google_Service_Exception) 
{
    // Handle error
    printf($request);
} 
else 
{
    printf("Permission ID: %s
", $request->id);
}