hmm thinking the other way arround. In case we add a new property which would be forgotten in clear(), this would be considered a bug. this bug would be proved by a failing test-case and therefore fixed. So this would lead to something we have here in this PR.

Therefore I think we should have one test, which creates a criteria changes more or less every property of it, assert it is not equal to a plain criteria anymore, but will be equals again after calling clear(). One separate Test per Property seems not worth to blow up the wohle suite...