Allow for Hibernate extensions discovery via OSGi blueprints
It is not possible to use a ServiceContributor when using the OSGi boostrap via OsgiSessionFactoryService. The getService method:
throws an org.hibernate.service.UnknownServiceException. This is due to the fact the contributor is not discovered via the Java Service Loader mechanism. OsgiSessionFactoryService should handle contributors in a similar fashion as integrators and look them up via the OSGi ServiceTracker.
Also, the code should add some error handling. Currently an exception seems to get just swallowed.
Closing resolved issued in preparation for releasing 4.3.6.