UAF13 — UML::Property.defaultValue has upper multiplicity of 1 even though Property is a MultiplicityElement

UML makes it hard/impossible to provide defaultValues for properties that have upper multiplicity higher than 1 since the defaultValue is limited to 1 ValueSpecification. While an OpaqueExpression could be used to provide a result of more than 1 element, this still requires execution of extra metaclass associations and the digital trail to Literals or InstanceValue's. Recommend changing the multiplicity to 0 .. *.