Fixes #58 - Do not explicitly add the persistenceUnitRootURL of a PersistenceUnit to null and add the URL to that persistence unit’s jar files. Hibernates Ejb3Configuration scans both locations automatically anyway, and if the persistence unit root URL is null then Hibernate logs a message at the error level. Also, URLs can only be scanned once. They should not occur in both the list of jars for that persistence unit AND as the root URL