retrieving refresh_token from google

[pichsenmeister]

I have integrated the phonegap sdk and the php server sdk in my application.

I have managed to get to the point, where I can call the me() method of the request_object.
I would like to retrieve to refresh_token, but I can't find a way to do that. What's the supposed way to do that in PHP?

$request_object = $this->oauth->auth('google');
$me = $request_object->me();
Log::debug($me);