An often used case of the proxy factory is to override interface methods by
creating an (aggregatable) proxy, then overriding certain interfaces. Single
methods of an overridden interface are implemented differently while the rest of
the methods are delegated to the target object. This way, one first has to
obtain a reference to the target object BEFORE calling setDelegator() [=>
because this would return the overridden interface].
A problem with delegation occured when the target object is itself a proxy
factory object (which has been registered at the compiler's UNO environment).

QA:
Because of the fact that the last stakeholders of the deprecated proxy factory
code are base and accessibility, and the fact that changes to the proxy factory
are highly sensible, I would strongly recommend to verify this issue generally
testing base and accessibility. There is also an old task #114513# which must be
verified again.