- Changed the API server so that for admission webhooks that have a URL matching the hostname 'localhost' or a loopback IP address, the connection supports HTTP/2 where it could be negotiated.
   ([#122558](https://github.com/kubernetes/kubernetes/pull/122558), [@linxiulei](https://github.com/linxiulei))

- Client-go: Clients can request protobuf and json and correctly negotiate with the server for JSON for CRD objects, allowing all client libraries to request protobuf if it is available.  If an error occurs negotiating a watch with the server, the error is immediately return by the client `Watch()` method instead of being...