Google + got new APK update for all Android 4.1 mobile devices. The developers have pushed this update with all the current bug fixes and app's performance improvement. We have the official change-log of this update below you can give you the exact idea about this Google+ update.
Official change-log/announcement of this update saying that app has,
Bug Fixes &
Security Enhancement to remove spam content and fake users.
Most important change we found is security enhancement, developers have added new security feature in the app called fake user removal, which will remove the spam content and spam users from the Google + and to give you the original content and news in the timeline.
Will update you here, if we found any other change in the app.
Go through the below link to download the APK file of this update
Google + v9.20.0 APK