OSGi event class should not be extended

http://svn.apache.org/repos/asf/sling/trunk/contrib/extensions/distribution/api/src/main/java/org/apache/sling/distribution/event/DistributionEvent.java
extends the OSGi event class which is a dangerous thing as handlers can't assume to get such an instance, they might simply get an OSGi event object.
As the whole point seems to be to create the topic out of the type, why not make an utility method out of it or add is as a paramter of the enumeration, so DistributionEventType.PACKAGE_CREATION.getEventTopic() returns the value.