This allows separation of concerns and makes the type system extensible. If
the type does not implement the necessary API, it falls back to using
instanceof.
This will allow for additional processing before actually triggering the
warnings. For the sake of this commit, though, we just keep with existing
functionality.
Note that, even though it's permitted, the validator still needs to be
modified to permit useful cases. In particular, I need weak abstract and
strong concrete methods for use in traits.
Mike Gerwitz