Can't we just have this exception contain some of the information stated here?

http://www.hibernate.org/116.html#A5

"If you use lazy loading with proxies (default for all classes in Hibernate 3), Hibernate needs to subclass your class at runtime. It can't do this if you have a private no-argument constructor. As per documentation, at least package visibility is required."

This will save everyone the level of indirection of having to google this exception first.