As we could use named parameters (instead of Builder classes in Java), infix methods, lambdas with receivers, coroutines… it would be great to build a simple API (non-blocking), maybe simply using delegates, to delegate implementations of methods to the Java API.
As I’m rather new to Kotlin but really love it, it would be great to have experienced Kotlin developers onboard, also for suggestions and how to do it in idiomatic Kotlin code 
Kind regards
Johannes