hibernate/hibernate-orm — pull request #429 by elbeyati (2012-12-17 18:03:11+00:00)
Title: HHH-7870: Envers fails in Oracle when calculating the difference of an entity whose type has changed from String to non-String 

Clean up the code to work around Oracle empty string to null conversions. Previously this would have caused null pointer exceptions as it assumes both previous and new values are Strings after it has only checked one of them.