- Modify war/WEB-INF/appengine-web.xml, put in your GAE app ID.
- Modify src/gplusync.properties, fill all the properties according to the key.
- Create a Google+ page, and set its notification email to all@your_app_id.appspotmail.com (or twitter@..., weibo@...).
- Deploy to Google App Engine.
Share anything on Google+ with the page created above as explicit receipt.