populateTShapedGraph();

    assertThat(graph.edges())
        .containsExactly(
            EndpointPair.unordered(1, 2),
            EndpointPair.unordered(1, 4),
            EndpointPair.unordered(1, 3),
            EndpointPair.unordered(4, 5))
        .inOrder();
  }

  @Test
  public void stableIncidentEdgeOrder_adjacentNodes_returnsInConnectingEdgeInsertionOrder() {

    populateTShapedGraph();

    assertThat(graph.edges())
        .containsExactly(
            EndpointPair.unordered(1, 2),
            EndpointPair.unordered(1, 4),
            EndpointPair.unordered(1, 3),
            EndpointPair.unordered(4, 5))
        .inOrder();
  }

  @Test
  public void stableIncidentEdgeOrder_adjacentNodes_returnsInConnectingEdgeInsertionOrder() {

    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

   *
   * <p>Note: This default implementation is overkill (but valid) for an unordered container. An
   * equally valid implementation for an unordered container is to throw an exception. The chosen
   * implementation, however, has the advantage of working for insertion-ordered containers, as
   * well.
   */
  @Override
  public List<Integer> order(List<Integer> insertionOrder) {

  public static <S> ElementOrder<S> unordered() {
    return new ElementOrder<>(Type.UNORDERED, null);
  }

  /**
   * Returns an instance which specifies that ordering is guaranteed to be always be the same across
   * iterations, and across releases. Some methods may have stronger guarantees.
   *
   * <p>This instance is only useful in combination with {@code incidentEdgeOrder}, e.g. {@code

  public static <S> ElementOrder<S> unordered() {
    return new ElementOrder<>(Type.UNORDERED, null);
  }

  /**
   * Returns an instance which specifies that ordering is guaranteed to be always be the same across
   * iterations, and across releases. Some methods may have stronger guarantees.
   *
   * <p>This instance is only useful in combination with {@code incidentEdgeOrder}, e.g. {@code

  }

  @Test
  public void edges_containsOrderMismatch() {
    addEdge(N1, N2, E12);
    EndpointPair<Integer> endpointsN1N2 = EndpointPair.unordered(N1, N2);
    EndpointPair<Integer> endpointsN2N1 = EndpointPair.unordered(N2, N1);
    assertThat(network.asGraph().edges()).doesNotContain(endpointsN1N2);
    assertThat(network.asGraph().edges()).doesNotContain(endpointsN2N1);
  }

  @Test

     */
    return Collector.of(
        () -> new ImmutableSortedMap.Builder<K, V>(comparator),
        (builder, input) -> builder.put(keyFunction.apply(input), valueFunction.apply(input)),
        ImmutableSortedMap.Builder::combine,
        ImmutableSortedMap.Builder::buildOrThrow,
        Collector.Characteristics.UNORDERED);
  }

   *
   * <p>Note: This default implementation is overkill (but valid) for an unordered container. An
   * equally valid implementation for an unordered container is to throw an exception. The chosen
   * implementation, however, has the advantage of working for insertion-ordered containers, as
   * well.
   */
  @Override
  public List<String> order(List<String> insertionOrder) {

   *
   * <p>Note: This default implementation is overkill (but valid) for an unordered container. An
   * equally valid implementation for an unordered container is to throw an exception. The chosen
   * implementation, however, has the advantage of working for insertion-ordered containers, as
   * well.
   */
  @Override
  public List<Integer> order(List<Integer> insertionOrder) {