EndpointPair.ordered(N1, N2),
        EndpointPair.ordered(N2, N1),
        EndpointPair.ordered(N1, N3),
        EndpointPair.ordered(N4, N4));
  }

  @Test
  public void endpointPair_undirectedNetwork() {
    MutableNetwork<Integer, String> undirectedNetwork =
        NetworkBuilder.undirected().allowsParallelEdges(true).allowsSelfLoops(true).build();
    undirectedNetwork.addNode(N0);