In OgmEntityEntryState method getStateFor, there's an attempt to retrieve the object from the persistence context. If the object is not found in the persistence context, then an exception is throw stating " 'entityEntry' must not be null ". This is not very descriptive and could easily be improved by passing something like "entityEntry: " + object as the "name" parameter to Contracts.assertNotNull. In this way the object's toString method will be called and appended to the exception output, allowing for easy identifcation of the object which is not in the persistence context.