Spliterator.SIZED | Spliterator.DISTINCT | Spliterator.NONNULL,
                    4))
        .expect(1, 1, 2, 3);
  }

  public void testFlatMapToLong_nullStream() {
    SpliteratorTester.ofLong(
            () ->
                CollectSpliterators.flatMapToLong(
                    Arrays.spliterator(new Long[] {1L, 0L, 1L, 2L, 3L}),
                    (Long i) -> i == 0L ? null : LongStream.of(i).spliterator(),

	OpConnectResponse

	// OpPing is a ping request.
	// If a mux id is specified that mux is pinged.
	// Clients send ping requests.
	OpPing

	// OpPong is a OpPing response returned by the server.
	OpPong

	// OpConnectMux will connect a new mux with optional payload.
	OpConnectMux

	// OpMuxConnectError is an  error while connecting a mux.
	OpMuxConnectError

	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[OpConnect-1]
	_ = x[OpConnectResponse-2]
	_ = x[OpPing-3]
	_ = x[OpPong-4]
	_ = x[OpConnectMux-5]
	_ = x[OpMuxConnectError-6]
	_ = x[OpDisconnectClientMux-7]
	_ = x[OpDisconnectServerMux-8]
	_ = x[OpMuxClientMsg-9]
	_ = x[OpMuxServerMsg-10]
	_ = x[OpUnblockSrvMux-11]