*
   * @return {@code true} if the network was modified as a result of this call
   * @throws IllegalArgumentException if {@code edge} already exists in the graph and does not
   *     connect {@code nodeU} to {@code nodeV}
   * @throws IllegalArgumentException if the introduction of the edge would violate {@link
   *     #allowsParallelEdges()} or {@link #allowsSelfLoops()}
   */
  @CanIgnoreReturnValue

      "Edge %s that was used to generate this set is no longer in the graph.";
  static final String REUSING_EDGE =
      "Edge %s already exists between the following nodes: %s, "
          + "so it cannot be reused to connect the following nodes: %s.";
  static final String MULTIPLE_EDGES_CONNECTING =
      "Cannot call edgeConnecting() when parallel edges exist between %s and %s. Consider calling "
          + "edgesConnecting() instead.";

  @Test
  public void equivalent_connectionsDiffer() {
    network.addEdge(N1, N2, E12);
    network.addEdge(N1, N3, E13);

    MutableNetwork<Integer, String> g2 = createNetwork(edgeType);
    // connect E13 to N1 and N2, and E12 to N1 and N3 => not equivalent
    g2.addEdge(N1, N2, E13);
    g2.addEdge(N1, N3, E12);

    assertThat(network).isNotEqualTo(g2);
  }

    this.allowsParallelEdges = allowsParallelEdges;
    return this;
  }

  /**
   * Specifies whether the network will allow self-loops (edges that connect a node to itself).
   * Attempting to add a self-loop to a network that does not allow them will throw an {@link
   * UnsupportedOperationException}.
   *
   * <p>The default value is {@code false}.
   */

    cache.getUnchecked(objectWithHash(0));
    CacheTesting.processPendingNotifications(cache);
    assertEquals(1, removalListener.getCount());
  }

  public void testUpdateRecency_onGet() {
    IdentityLoader<Integer> loader = identityLoader();
    final LoadingCache<Integer, Integer> cache =
        CacheBuilder.newBuilder().maximumSize(MAX_SIZE).build(loader);
    CacheTesting.checkRecency(

    GraphBuilder<N1> castBuilder = cast();
    return new ImmutableGraph.Builder<>(castBuilder);
  }

  /**
   * Specifies whether the graph will allow self-loops (edges that connect a node to itself).
   * Attempting to add a self-loop to a graph that does not allow them will throw an {@link
   * UnsupportedOperationException}.
   *
   * <p>The default value is {@code false}.
   */

    cache.getUnchecked(objectWithHash(0));
    CacheTesting.processPendingNotifications(cache);
    assertEquals(1, removalListener.getCount());
  }

  public void testUpdateRecency_onGet() {
    IdentityLoader<Integer> loader = identityLoader();
    final LoadingCache<Integer, Integer> cache =
        CacheBuilder.newBuilder().maximumSize(MAX_SIZE).build(loader);
    CacheTesting.checkRecency(

     *
     * @return this {@code Builder} object
     * @throws IllegalArgumentException if {@code edge} already exists in the network and does not
     *     connect {@code nodeU} to {@code nodeV}
     * @throws IllegalArgumentException if the introduction of the edge would violate {@link
     *     #allowsParallelEdges()} or {@link #allowsSelfLoops()}
     */
    @CanIgnoreReturnValue

  /**
   * Returns true if the edges in this graph are directed. Directed edges connect a {@link
   * EndpointPair#source() source node} to a {@link EndpointPair#target() target node}, while
   * undirected edges connect a pair of nodes to each other.
   */
  @Override
  boolean isDirected();

  /**
   * Returns true if this graph allows self-loops (edges that connect a node to itself). Attempting

  @Test
  public void equivalent_connectionsDiffer() {
    network.addEdge(N1, N2, E12);
    network.addEdge(N1, N3, E13);

    MutableNetwork<Integer, String> g2 = createNetwork(edgeType);
    // connect E13 to N1 and N2, and E12 to N1 and N3 => not equivalent
    g2.addEdge(N1, N2, E13);
    g2.addEdge(N1, N3, E12);

    assertThat(network).isNotEqualTo(g2);
  }