In my opinion it is expectable from a Java-developer to migrate his techniques to Kotlin as its not too hard from what I know from my own experiences. Moreover, Kotlin is definitely the future language for native Android apps, and anyone who refuses to improve on this aspect can blame himself for not accepting the most basic programmer rule — moving on and learning new things. Btw.: I for myself cannot understand how someone would choose Java if Kotlin was an option. If you ever used Kotlin you don’t want to go back.
