The Javadoc notes it, but this Wiki doc does not. The Map contents for
SessionFactory.getAllClassMetadata() changed from being keyed by Class
to being keyed by String. If you rely on this you may see
ClassCastExceptions or you may not find expected values in the Map
because you are looking using the wrong kind of key. 

From the Javadoc:

"Since:
3.0 changed key from Class to String"