Hi, I've been playing with Undertow under the Java 9 module system (i.e. not only compile/run with Java 9 but actually make it a modular JAR).

It's too early to say whether the experiment succeeds or not, but I came across some small things which will be an in issue with Jigsaw but can already be fixed right now without any impact on earlier Java versions.

I'll send a PR asap.