CalDAV Binding with Google Calendar

I’m stuck on configure CalDAV binding to work with google calendar.
I use GCal with 1.8.3 using an old binding for 1.5 changed to use oauth 2.0 and it work.
I tried to port it to 2.0, but it does not work. I’m trying now to use native CalDAV bindings following variuos tutoriar, here one: but I cannot configure to access to my Google Calendar, that work with 1.8.3.

Do someone configured GCal with CALDAV binding? How make it work? I’m stuck on this, and miss only this step to move to 2.0

Any help would be appreciated.