code: func (i *interceptor) Register(stream pb.ChaincodeSupport_RegisterServer) error {
  	is := &interceptedStream{
  		incMessages:  make(chan *pb.ChaincodeMessage, 1),
  		stream:       stream,
  		ServerStream: stream,
  		auth:         i.auth,
  	}
  	msg, err := stream.Recv()
  	if err != nil {
  		return fmt.Errorf("Recv() error: %v, closing connection", err)
  	}
  	err = is.auth(msg, is.ServerStream)
  	if err != nil {
  		return err
  	}
  	is.incMessages <- msg
  	close(is.incMessages)
  	return i.next.Register(is)
  }
docs: // Register makes the interceptor implement ChaincodeSupportServer