EJB3PostLoadEventListener is created by EventListenerConfigurator with its default constructor:

listenerConfig.setPostLoadEventListeners(
new PostLoadEventListener[] { new EJB3PostLoadEventListener(), new DefaultPostLoadEventListener() }
);

The problem is that it has a callbackHandler field called which remains null, and there is no check in the postLoad method before invoking callbackHandler.postLoad( entity );. This causes a NullPointerException to be thrown there in a few situations.

The fix is simple. H+In the EJB3PostLoadEventListener's postLoad() method, replace:

public void onPostLoad(PostLoadEvent event) {
Object entity = event.getEntity();
callbackHandler.postLoad( entity );
}
by:

public void onPostLoad(PostLoadEvent event) {
if (callbackHandler == null) return;
Object entity = event.getEntity();
callbackHandler.postLoad( entity );
}

This would prevent the NullPointerException to be thrown when there is no callbackHandler.