The Javassist enhancer has the same behavior as the ByteBuddy enhancer (see org.hibernate.bytecode.enhance.internal.javassist.EntityEnhancerl#collectCollectionFields), so although the default in 5.3 has been changed, the issue should be present in 5.1 as well. (javassist enhancer does not make use of the ExtendedSelfDirtinessTracker interface, but that is an implementation detail)