Easiest way to enable Google authentication for GWT application? (non-GAE-hosted)

Question

What is the easiest way to enable existent GWT application authenticate users using Google account? I tried googling (lol) it but have found no solutions that could work out of the box. Is there a library to solve this problem in like 10 lines of code?

P.S. The application I've mentioned isn't hosted at Google Apps if it matters.

Answer 1

I have been looking at gwt-oauth2 for this purpose recently. It looks pretty decent, and the docs are straightforward. Perhaps it could be of interest.