[Pharo-project] Zinc-SSO OAuth2 Google offline access

After some struggle to understand OAuth2 and Google Calendar API, I managed to insert a calendar entry. Now, I want to be able to manipulate the calendar, without the user being logged on, in their browser - which is "offline" access according to the Google docs [1] (I'm not sure whether this is an OAuth2 feature, or a Google API feature). I noticed that the ZnGoogleOAuth2Session is coded for "online" access. Should I start coding a ZnGoogleOAuth2OfflineSession - is this the right approach? What's the best way to contribute the code - just make changes in Zinc-SSO-OAuth2-Core package, for later merging? [1] https://developers.google.com/accounts/docs/OAuth2WebServer