EJB3 has incomplete entity management

After to have (zero)configured your session beans, it is possible to add AS behaviors using AS specific deployment descriptors... and that's good because portability becomes only a deploy configuration before packaging...
entities are not ready, seems to be not possible to provide entity manager specific behaviors at configuration level, as written in hibernate documentation:

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.

sob...