Refresh self from the server-provided protobuf.
        Helper for :meth:`from_pb` and :meth:`reload`.

def _update_from_pb(self, instance_pb):
        """Refresh self from the server-provided protobuf.
        Helper for :meth:`from_pb` and :meth:`reload`.
        """
        if not instance_pb.display_name:  # Simple field (string)
            raise ValueError("Instance protobuf does not contain display_name")
        self.display_name = instance_pb.display_name
        self.type_ = instance_pb.type
        self.labels = dict(instance_pb.labels)
        self._state = instance_pb.state