Discussing this with Guillaume Smet, we agreed that the current wording is sufficient. As for the first case, we discourage joint usage of legacy and new style, implying that validation may occur twice. While this suggests that the group conversions local to each @Valid apply, it seems fine to not specify the behavior in that discouraged usage.

As for the second case, we currently say that @Valid should be put to the inner-most type argument. We can't see a use case that'd require to specify @Valid another time at an upper container, so we'll leave that undefined. The ultimate group conversions can always be given on the inner-most @Valid, so that's not a use case for having multiple @Valid in one line of containers either. If needed by an actual use case, a behavior can be mandated in a future revision of the spec.