yep. I found my self getting pretty cozy ( out of necessity :) ) with the changes in netty 4+ so I'm pretty familiar. I you do me a favor and add the following i'm your tests

https://github.com/unfiltered/unfiltered/blob/d8435e23ec02a4ed8123bfe84ed61c234bf37543/spec/src/main/scala/netty/Served.scala#L20-L22

This was very helpful in letting me know where we had leaks but it was removed from our default test harness by accident when we upgraded from specs to specs2. I'll open a separate bug to add it back in. That settings is really the best way to catch resource leak issues. Not having it is just asking for regressions later.