Older Configuration Admin Service specifications allowed multi-value properties to be stored as either arrays or Vector objects. Recently the specification was changed to support Collection objects.
The problem is that vectors are sorted, much like lists, while collections do not define an order.
The upcoming specification release of the Configuration Admin Service will clarify that configuration properties provided in a Collection object supporting ordering (e.g. Vector or List) must maintain their order when persisted and provided back.
For our implementation this should not be a problem since we are internally using ArrayLists. Still we might want to cross check and implement a unit or integration test to validate the claim.