I’m coding since decades(!) My first programs were in Fortran66 and I remember the switch to Ansi Fortran77.
Since then I have not only learned, but even worked in lots of languages and db-systems. So you have a glimps of my history.
I’m quite familiar with Java since 5 years now. (At least I thought! 
), have made about 10 (real used) applications in Java so far. and all are working fine.
Nevertheless I’m not that firm to know all constructions really good. Or frankly, I think I dont know/use many of the sophisticated modern ones! (Vintage programing style? 
)
As i dont really care if type declaration is before or after variable and complex constructs only can be learned using them: my learning style now is combining sniplets, and later on getting used to the backgrounds. And: I like Youtube!
Using a good IDE like AndroidStudio protects you from messing up with Gradle/Mavin/Groovy. …
That’s exactly the goal of Kotlin: Get rid of all these boiler plates! Not only within the language, but even in the whole buildingprozess!
So for my android apps so far there was no need to touch them, not even “manifest”. (I not even looked at them). That might be different, as soon as I have to manage rights, access, …
Thx for your hints and links. I’l watch them! There’s a lot to learn.