Minor Description
stillalex, due to missing nullability annotations in org.apache.jackrabbit.oak.spi.commit,Validator interface, some old implementations in the security code base like TokenValidator perform redundant checks for null that would only occur in case of invalid sequences of Validator.childNodeAdded followed by Validator.childNodeChanged (or similar examples with delete/add and delete/change). I would prefer to verify the expected non-null state and have the subsequent not perform extra checks for null that are never executed.