Regarding documentation, while you're right, I'd like to point out that Kotlin intentionally has a minimal standard library. The Java standard library is Kotlin's standard library (modulo some minor additions), and Kotlin is designed to make using the same APIs a lot nicer -- not to replace them with Kotlin-specific APIs. The preferred approach for creating a "Kotlin wrapper" if one is necessary is simply adding extension methods to the Java class. So while more detailed Kotlin documentation would certainly help, it requires much thinner documentation than other JVM languages that package their own rich standard libraries.
> The preferred approach for creating a "Kotlin wrapper" if one is necessary is simply adding extension methods to the Java class.
You nailed it. I think that this is ultimately something that JetBrains must stress in their documentation and have extensive examples on how to go about doing this if Kotlin is to get much more widespread adoption.
