Spring Caching not backward-compatible

When migrating from Spring 3 to Spring 5, I have noticed that caching is not backward-compatible.

In Spring 3, it is possible to provide a null value as a cache key. In Spring 5, this causes the execution to break with an exception (Null key returned for cache operation (maybe you are using named params on classes without debug info?). Should caching not be backward compatible in this regard?

Comment From: TheRealDragan

Closing issue as further investigation showed that this is caused by the change in the keygenerator being used; null values were never allowed for cache