In 220.127.116.11, Value.equals(Value) returns false if either value "has been
accessed" or the values were not "acquired from the same session", even if the
two values are in fact "equal". This is misleading.
Proposal: throw an exception in each of these cases.
(Note: We're overloading, not overriding, the inherited equals(Object) method.
So we are free to throw a RepositoryException here.)