Hi,
few weeks ago I was looking for a game engine to dev some on Android, I work fine with Java+Android Studio, and this engine seem to be the choice to me.
I actually have created some things (using jcenter), you know how clean and easy is Android Studio with gradle and external things, but… That is not in the docs.
I don’t think there is an absolute “correct” way. It mostly depends on your needs.
I mostly just use the jar files on my projects since I am not in need to build from source. But there is one project in plans where I may need to have the source code so I can modify it to my own game project needs and i would use gradle.
you can also use grade in your project with jme like in this example. I hope it helps: