Maybe I'm wrong about the state of Java in Android today - it's been a few years since I did that work full-time. But I do remember when Kotlin broke on to the scene in 2015, and most of us were thrilled to finally move beyond Java 7! The embrace of a non-Java language was grassroots and genuine; Google's adoption came several years later.

J++ though, now that is a blast from the past! I think I still have a J# book from my student days, somewhere :)