Verifying app sources
An .apk file has got the same format as a .zip file. If the used archiver does not detect it as such, you can change the extension .apk to .zip. With my system, content of primore.apk looks like follows:
According to Wikipedia, classes.dex contains the program code. Of course other files also influence program flow, but certainly the program code is the most important part of the app. Therefore verification primarily is about classes.dex.
For that aim you have to download Android Studio, have to extract Primore sources and have to open them in Android Studio. After release compilation, the classes.dex file is to extract from built .apk file, too. For a developer this is a familiar procedure. Therefore I will not describe it any further.
Content of both classes.dex files that were extracted from archives, should be equal. If this should be not the case, then we absolutely should clarify the cause of this problem. Please give me a hint in this case. It could be caused by Android Studion version - currently I use version 2.0 under Linux.