public boolean contains(@CheckForNull Object obj) {
    if (!(obj instanceof EndpointPair)) {
      return false;
    }
    EndpointPair<?> endpointPair = (EndpointPair<?>) obj;

    if (graph.isDirected()) {
      if (!endpointPair.isOrdered()) {
        return false;
      }

      Object source = endpointPair.source();
      Object target = endpointPair.target();

    assertThat(graph.hasEdgeConnecting(EndpointPair.unordered(1, 2))).isFalse();
    assertThat(graph.hasEdgeConnecting(EndpointPair.unordered(2, 1))).isFalse();
  }

  @Test
  public void hasEdgeConnecting_undirected_correct() {
    graph = ValueGraphBuilder.undirected().build();
    graph.putEdgeValue(1, 2, "A");
    assertThat(graph.hasEdgeConnecting(EndpointPair.unordered(1, 2))).isTrue();
  }

  @Test

          // operations only in weird cases like checking for an EndpointPair<ArrayList> in a
          // Network<LinkedList>.
          @SuppressWarnings("unchecked")
          @Override
          public boolean contains(@CheckForNull Object obj) {
            if (!(obj instanceof EndpointPair)) {
              return false;
            }
            EndpointPair<?> endpointPair = (EndpointPair<?>) obj;

          // operations only in weird cases like checking for an EndpointPair<ArrayList> in a
          // Network<LinkedList>.
          @SuppressWarnings("unchecked")
          @Override
          public boolean contains(@CheckForNull Object obj) {
            if (!(obj instanceof EndpointPair)) {
              return false;
            }
            EndpointPair<?> endpointPair = (EndpointPair<?>) obj;

    assertThat(graph.hasEdgeConnecting(EndpointPair.unordered(1, 2))).isFalse();
    assertThat(graph.hasEdgeConnecting(EndpointPair.unordered(2, 1))).isFalse();
  }

  @Test
  public void hasEdgeConnecting_undirected_correct() {
    graph = ValueGraphBuilder.undirected().build();
    graph.putEdgeValue(1, 2, "A");
    assertThat(graph.hasEdgeConnecting(EndpointPair.unordered(1, 2))).isTrue();
  }

  @Test

   * any, specified by {@code endpoints}).
   *
   * <p>Unlike the other {@code EndpointPair}-accepting methods, this method does not throw if the
   * endpoints are unordered and the network is directed; it simply returns {@code false}. This is
   * for consistency with {@link Graph#hasEdgeConnecting(EndpointPair)} and {@link
   * ValueGraph#hasEdgeConnecting(EndpointPair)}.
   *
   * @since 27.1
   */

  }

  @Override
  public Set<E> edgesConnecting(EndpointPair<N> endpoints) {
    return delegate().edgesConnecting(endpoints);
  }

  @Override
  public Optional<E> edgeConnecting(N nodeU, N nodeV) {
    return delegate().edgeConnecting(nodeU, nodeV);
  }

  @Override
  public Optional<E> edgeConnecting(EndpointPair<N> endpoints) {
    return delegate().edgeConnecting(endpoints);
  }

      while (graph.edges().size() < NUM_EDGES) {
        graph.putEdge(getRandomElement(nodeList, gen), getRandomElement(nodeList, gen));
      }
      ArrayList<EndpointPair<Integer>> edgeList = new ArrayList<>(graph.edges());

      assertThat(graph.nodes()).hasSize(NUM_NODES);
      assertThat(graph.edges()).hasSize(NUM_EDGES);
      AbstractGraphTest.validateGraph(graph);

            .putEdgeValue(2, 3, "2-3")
            .putEdgeValue(1, 2, "1-2")
            .build();

    assertThat(graph.incidentEdges(2))
        .containsExactly(
            EndpointPair.ordered(2, 1), EndpointPair.ordered(2, 3), EndpointPair.ordered(1, 2))
        .inOrder();
  }

  @Test
  public void immutableValueGraphBuilder_incidentEdgeOrder_stable() {
    ImmutableValueGraph<Integer, String> graph =

  }

  @Override
  public boolean putEdge(N nodeU, N nodeV) {
    return backingValueGraph.putEdgeValue(nodeU, nodeV, Presence.EDGE_EXISTS) == null;
  }

  @Override
  public boolean putEdge(EndpointPair<N> endpoints) {
    validateEndpoints(endpoints);
    return putEdge(endpoints.nodeU(), endpoints.nodeV());
  }

  @Override
  public boolean removeNode(N node) {
    return backingValueGraph.removeNode(node);