ArrayList<Object> edgeList = new ArrayList<>(network.edges());

      assertThat(network.nodes()).hasSize(NUM_NODES);
      assertThat(network.edges()).hasSize(NUM_EDGES);
      AbstractNetworkTest.validateNetwork(network);

      Collections.shuffle(edgeList, gen);
      int numEdgesToRemove = gen.nextInt(NUM_EDGES);
      for (int i = 0; i < numEdgesToRemove; ++i) {
        Object edge = edgeList.get(i);

  // Ideally, the ordering in test should never be updated.
  @Test
  public void stableIncidentEdgeOrder_edges_returnsInStableOrder() {
    assume().that(graph.incidentEdgeOrder().type()).isEqualTo(ElementOrder.Type.STABLE);

    populateStarShapedGraph();

    assertThat(graph.edges())
        .containsExactly(
            EndpointPair.ordered(2, 1),
            EndpointPair.ordered(1, 4),

    ImmutableMultimap.Builder<Character, Character> graphMapBuilder = ImmutableMultimap.builder();
    for (String edge : edges) {
      checkArgument(
          edge.length() == 2, "Expecting each edge to consist of 2 characters but got %s", edge);
      char node1 = edge.charAt(0);
      char node2 = edge.charAt(1);
      graphMapBuilder.put(node1, node2);

  // Ideally, the ordering in test should never be updated.
  @Test
  public void stableIncidentEdgeOrder_edges_returnsInStableOrder() {
    assume().that(graph.incidentEdgeOrder().type()).isEqualTo(ElementOrder.Type.STABLE);

    populateTShapedGraph();

    assertThat(graph.edges())
        .containsExactly(
            EndpointPair.unordered(1, 2),
            EndpointPair.unordered(1, 4),

    assertThat(edges).hasSize(2);
    assertThat(edges).contains(EndpointPair.unordered(N1, N1));
    assertThat(edges).contains(EndpointPair.unordered(N1, N2));
    assertThat(edges).contains(EndpointPair.unordered(N2, N1)); // equal to unordered(N1, N2)

    // ordered endpoints not compatible with undirected graph
    assertThat(edges).doesNotContain(EndpointPair.ordered(N1, N2));

    assertThat(edges).hasSize(2);
    assertThat(edges).contains(EndpointPair.unordered(N1, N1));
    assertThat(edges).contains(EndpointPair.unordered(N1, N2));
    assertThat(edges).contains(EndpointPair.unordered(N2, N1)); // equal to unordered(N1, N2)

    // ordered endpoints not compatible with undirected graph
    assertThat(edges).doesNotContain(EndpointPair.ordered(N1, N2));

      ArrayList<Object> edgeList = new ArrayList<>(network.edges());

      assertThat(network.nodes()).hasSize(NUM_NODES);
      assertThat(network.edges()).hasSize(NUM_EDGES);
      AbstractNetworkTest.validateNetwork(network);

      Collections.shuffle(edgeList, gen);
      int numEdgesToRemove = gen.nextInt(NUM_EDGES);
      for (int i = 0; i < numEdgesToRemove; ++i) {
        Object edge = edgeList.get(i);

 *       locks---to each of the acquired locks, an edge from the soon-to-be-acquired lock is either
 *       verified or created.
 *   <li>If a new edge needs to be created, the outgoing edges of the acquired locks are traversed
 *       to check for a cycle that reaches the lock to be acquired. If no cycle is detected, a new
 *       "safe" edge is created.
 *   <li>If a cycle is detected, an "unsafe" (cyclic) edge is created to represent a potential

  }

  @Override
  @Test
  public void edges_checkReturnedSetMutability() {
    assume().that(graphIsMutable()).isTrue();

    Set<String> edges = network.edges();
    UnsupportedOperationException e =
        assertThrows(UnsupportedOperationException.class, () -> edges.add(E12));
    addEdge(N1, N2, E12);
    assertThat(network.edges()).containsExactlyElementsIn(edges);
  }

  @Override
  @Test

 *   <li>graphs whose nodes/edges are insertion-ordered, sorted, or unordered
 *   <li>graphs whose edges have associated values
 * </ul>
 *
 * <p>{@code ValueGraph}, as a subtype of {@code Graph}, explicitly does not support parallel edges,
 * and forbids implementations or extensions with parallel edges. If you need parallel edges, use
 * {@link Network}. (You can use a positive {@code Integer} edge value as a loose representation of