SYSML21 — Error in constraint validateAssignmentActionUsageReferent

The constraint validateAssignmentActionUsageReferent is described as

An AssignmentActionUsage must have an ownedMembership that is not an OwningMembership and whose memberElement is a Feature.

This is intended to support the derivation of AssignmentActionUsage::referent, however, the constraint deriveAssignmentActionUsageReferent is

The referent of an AssignmentActionUsage is the first Feature that is the memberElement of a ownedMembership that is not a FeatureMembership.

Note that the derivation only excludes FeatureMembershps, not all OwningMemberships. Indead, a referent that is a feature chain will be owned by the AssignmentActionUsage using an OwningMembership.