Actually, we cannot replace the whole of ModelMBeanInfoSupport.
My suggestion above won't work because it will break
We can't use an alternate implementation because not all
the classes are interfaces.
I think we can still use our DescriptorSupport code
to get the serialization fix and performance improvements.
But I'll probably have to introduce
some kind of compatiblity mode for older versions that don't
have the new class on the client or use writeReplace()?