Steve, I've no idea why, but it works now.

I've played around with your tests and it works fine for single entities as well as defined by JPA. So I doublechecked my configs again and in our app it didn't work. So I started from scratch, did the whole setup again. And what can I say?! It works. So I was interested in what stupid mistake I've done and compared the changes from my branch (did not work) and from master (works now) and they're exactly the same. Then I copied the configs from the branch to master and it still works. The branch works fine now as well.

I deleted the wildlfy tmp and data directories as we sometimes get this error on wildfly startup:
Caused by: java.lang.ClassCastException: org.dom4j.DocumentFactory cannot be cast to org.dom4j.DocumentFactory

There's only one dom4j jar in the project and after deleting tmp/data in wildfly it works again. So maybe that fixed something. I've no other idea, really. Couple of ours wasted.

Feel free to reject this issue. Thx a lot for your support and the test!