UMLR — UML2 Property collaborationRole should be removed

The collaborationRole property of Collaboration does not appear to be needed and could be removed. A Collaboration's ownedAttributes subsets inherited derived union role, and therefore represent the roles in a Collaboration. Since Property is extended to be a ConnectableElement, collaborationRole is redundant with ownedAttributes. In addition, the description does not seem to make sense. A collaborationRole can't reference connectable elements (possibly contained in another classifier) because the roles of a Collaboration must be parts or ownedAttributes of that Collaboration. The roleBindings of a CollaborationUse bind the roles of its Collaboration type to parts of some other classifier.

However, there could be another interpretation of collaborationRole. If Collaborations are used to represent patterns, then a Collaboration's ownedAttributes may represent the common part of the pattern while the collaborationRoles represent the variable part. Instantiating the pattern with a CollaborationUse may then mean that the Classifier owning the CollaborationUse would need to directly contain the common parts (copies of them from the collaboration), and require roleBindings to the variable parts. In this case, collaborationRole parts would require bindings (and therefore subclass role) while ownedAttributes don't (and wouldn't subclass role)?

In any case, the purpose of property collaborationRole is unclear and should be amplified in the specification to distinguish it from ownedAttributes and how it should be used.