This is the stock SMS app from AOSP, configured as an Android Studio project so that it can be built without having to download and compile all of AOSP.
... provided that you also accept transfer of the app in Play (although the app is unpublished at Play, Google does not let me remove it because of active installations). If you agree, send a message to alper.goplay@gmail.com with your transaction ID and developer ID, transfer at Play will be performed first, then Github.