No, there will be no implementation of this Interface within my framework use (can't tell for anything beside it obviously). I didn't plan to use Javassist just to get the validation working, I would then rather go with a different approach for now.

I think in an earlier implementation of my code it worked, although I believe that I didn't do something basically different then. I used 4.3 validation, though and can remember that I never got it running with 5.x. Did something change for the validation between 4.3 and 5?