There was a regression in Netty 4.1.32-Final that a customer encountered, but we hadn't seen it because we don't update our Netty dependency very often.

We can catch issues early by testing against latest Netty release. The easiest way to do that is with a version range. It has the disadvantage of making builds non-repeatable, but the alternative of updating every month (which is Netty's patch release cadence) seems worse.