UPDM — Attribute stereotype has issues with non-navigable associations

This stereotype extends Property and according to the diagram, it must be the value of the "endType" meta-property of an EntityRelationship, which extends Association. This <<Attribute>> stereotype and the implied constraint are fine if the association roles are always navigable. If an association role is non-navigable or if the element at the end of the association cannot own properties, the association end property is owned by the association itself, making it difficult for the user to apply the <<Attribute>> stereotype to that property.

We'll add a constraint to "EntityAttribute" to explain that the stereotype is only applied to Properties that are owned by "EntityItem"s.