The primary target for metadata in EJB3 is annotations, but the EJB3 specification provides a way to override or replace the annotation defined metadata through an XML deployment descriptor. In the current release only pure EJB3 annotations overriding are supported. If you wish to use Hibernate specific features in some entities, you'll have to either use annotations or fallback to hbm files. You can of course mix and match annotated entities and entities describes in hbm files.

The unit test suite shows some additional XML file samples.