I believe I have found a regression error that started occurring since HHH-3957. It is both in the 1.2.2.GA release of Envers (Hibernate 3.3 compatible) and in the 3.5.x series. I am sure that it did not occur not in 1.2.1 GA.
This occurs when auditReader.find() is called for entities containing embedded components with default values. If the database contains a NULL value for a field in an embedded component with a default value, the returned entity does not contain NULL, but the default value.
I have created issue http://opensource.atlassian.com/projects/hibernate/browse/HHH-5288 for this, with a complete testcase.
Please have a look at it.
BTW there is also a very serious regression issue in the Hibernate core 3.5.x, which inhibits the use of generified collections (List< ? extends Object>). See Jira for the details. Apparently I'm not the only one, since has the highest number of votes for 3.5.x. I've tried the patch and it seems to work fine for me. I'd be very obliged if anyone of the Hibernate team could look at this too...