Change of behaviour for @Finalize between 2.3 and 2.4 release

In the 2.4 release note, in the ‘Potential Breaking Changes’ section, I see

The withType() method selects elements based on the public contract type rather than implementation type.

This might be the reason for my problem, but then I’m not sure how to understand this change of behavior and how to modify my RuleSource to cope with this change.