We are agreeing that @ConvertGroup can only be defined when @Valid is defined. This solves the problem of defining @ConvertGroup several times in the class hierarchy and avoid the problem of violating the Liskov substitution principle:

• @Valid can only be defined at the top level for params as per the existing rules
• @Valid can be defined on return values

We are adding a rule that enforce that @Valid can only be defined once per class hierarchy. This solves again the risk of defining it twice and thus being able to define @ConvertGroup twice which would trigger the Liskov BSOD.

There is one remaining problem: In case of parallel interfaces defining the same method, the return value can host constraints which means we could define @Valid on both interfaces and thus have parallel @ConvertGroup rules and contradictions. The easy solution is to add a provision rule forbidding to have @ConvertGroup twice in this case.

If we find a better solution over the week end we can change that