Yep, a build issue most likely. However I did not manage to make Hibernate work with Karaf and Aries JPA so I defaulted back to OpenJPA which works good in this setup.

There are some working examples: https://github.com/lburgazzoli/lb-karaf-examples-jpa/ but they require some manualt starting procedures (you need to restarte apache jpa containter service or make hibernate-osgi start before)