ProGuard writes the mapping file under the build directory of the project. Under normal circumstances all files and directories under the build dirs are excluded from version control. That is a bit of an issue if you want to be able to save that file with every release build. I always forget to this manually. So, let’s do that at build time with Gradle and while we are at it, we might as well rename our apk file, so we don’t have to do that manually either.