Split dependencies from own code
To avoid further license debacles and of course as a very well known coding best practice, you should of course not mix own code and dependencies (i.e. third-party libraries etc.)
As it has been discovered on Twitter in your directory Luca/app/src/main/java/de/culture4life/luca/util (permalink) you mix the third-party code Z85.java with your own code in TimeUtil.java e.g.
Why do you do so? Could not you just load it via gradle or so?
Or… by all means (if it is really not possible for technical reasons – which you should explain), use git submodules or so…
At the very very least, create a directory thirdPartyCode to place it in there. Then you can also exclude that dir from any strange comment stripper you run (#17 (closed)) to remove some comments – which you should not do anyway and is just bogus.
I'm no Android dev, but it seems very strange to copy and paste files. Also, this way, you can easily overlook outdated dependencies and security issues may be introduced. Despute the fact, that it is of course harder to maintain.