%FindGUID() attempts to locate the GUID of object for which we do not know the most specific type class.
This can happen when resolving the ID for an object that has been deleted, as sometimes occurs when dealing with
objects retrieved from the system journal for the purpose of synchronizing with another system.
This method assumes that the normal GUID resolution has failed and that if another object of a different MSTC exists within
the same root extent then it is the same object (same GUID). For example, class A is persistent and it has two sub classes - B and C.
An instance of B is created and assigned a GUID. At some future time, that instance of B is deleted and recreated as an instance of C using
the same ID value. The premise of %FindGUID is that the object having an OID of (id,"B") is the same object as that with an OID of (id,"C").