UML25 — Opposite ends of derived unions should be derived unions

Action::inputPin and Action::outputPin are both derived unions. Both also have opposite association owned ends that are not derived. While I don't think the metamodel is actually incorrect, those owned ends are implicitly derived unions too. So I think it would make more sense to make that explicit.

I've just picked two examples, however I believe there are more in the specification.

The FTF agrees that the other ends ought to be derived unions. Because all cases of this are associationowned
ends, this does not affect serialization. There are ten cases of this in the metamodel, which are the
opposite ends for:
DirectedRelationship::source
DirectedRelationship::target
Classifier::attribute
StructuredClassifier::role
Action::input
Action::output
RedefinableElement::redefinedElement
RedefinableElement::redefinitionContext
Namespace::member
Relationship::relatedElement