Writing in Kotlin really is a nicer experience and with near full access to all the legacy java libraries I would never want to switch back even with the small improvements java has made to be more like Kotlin. I highly suspect as the number of java devs that are exposed to Kotlin increases the number of devs happy to write in Java over Kotlin (or Scala) will decrease. Android going Kotlin first was in part justified by giving the decision makers a short period of a week or two to get adjusted away from java and see how they felt about the language in comparison
Google could just run OpenJDK on phones and toss all the garbage they built, but they're too proud. The GC and performance of ART isn't anywhere near OpenJDK
Most of the code was already written in Java. So I just used the tool to convert to Kotlin. Then I tried to infer how Kotlin works based on the generated code to write the rest. I don't feel proud about that project.
Good to know for my next Udemy course.