I have been exploring Kotlin at work for the past few months, and started experimenting with Netty recently. I decided to use Kotlin for my Netty explorations as I've found the coroutine support to be very pleasant for managing concurrent applications! This is partly a learning project, but maybe someone else will also find it useful to see Kotlin coroutine based http servers built on top of Netty!
https://github.com/anuragsoni/fiber