That's an interesting case for sure.

By iterating through the hierarchy via getClassHierarchy() we actually also see constraints declared on implemented interfaces, but in your case there is nothing to iterate through as no actual classes are involved at all. Not sure out of my head how we should handle re-defined default group sequences in this case (which are the reason for doing the hierarchy traversal).

You will never have an implementation of these interfaces? As a workaround, you might try using class based proxies with e.g. Javassist; that way the hierarchy traversal should kick in, but I agree that it also should work in the case you describe.