ImmutableGraph<String> immutableGraph = ImmutableGraph.copyOf(mutableGraph);

    assertThat(immutableGraph).isNotInstanceOf(MutableValueGraph.class);
    assertThat(immutableGraph).isEqualTo(mutableGraph);

    mutableGraph.addNode("B");
    assertThat(immutableGraph).isNotEqualTo(mutableGraph);
  }

  @Test
  public void copyOfImmutableGraph_optimized() {

    ImmutableGraph<String> immutableGraph = ImmutableGraph.copyOf(mutableGraph);

    assertThat(immutableGraph).isNotInstanceOf(MutableValueGraph.class);
    assertThat(immutableGraph).isEqualTo(mutableGraph);

    mutableGraph.addNode("B");
    assertThat(immutableGraph).isNotEqualTo(mutableGraph);
  }

  @Test
  public void copyOfImmutableGraph_optimized() {

 * graph.putEdge("bread", "bread");
 * graph.putEdge("chocolate", "peanut butter");
 * graph.putEdge("peanut butter", "jelly");
 *
 * // Building an immutable graph
 * ImmutableGraph<String> immutableGraph =
 *     GraphBuilder.undirected()
 *         .allowsSelfLoops(true)
 *         .<String>immutable()
 *         .putEdge("bread", "bread")
 *         .putEdge("chocolate", "peanut butter")

      ValueGraphBuilder.directed().allowsSelfLoops(true).expectedNodeCount(16);

  private static final ImmutableGraph<String> IMMUTABLE_GRAPH_A =
      GraphBuilder.directed().<String>immutable().addNode("A").build();
  private static final ImmutableGraph<String> IMMUTABLE_GRAPH_B =
      GraphBuilder.directed().<String>immutable().addNode("B").build();

    mutableValueGraph.addNode("A");
    ImmutableValueGraph<String, Integer> immutableValueGraph =
        ImmutableValueGraph.copyOf(mutableValueGraph);

    assertThat(immutableValueGraph.asGraph()).isInstanceOf(ImmutableGraph.class);
    assertThat(immutableValueGraph).isNotInstanceOf(MutableValueGraph.class);
    assertThat(immutableValueGraph).isEqualTo(mutableValueGraph);

    mutableValueGraph.addNode("B");

    return checkNotNull(graph);
  }

  @Override
  public ElementOrder<N> incidentEdgeOrder() {
    return ElementOrder.stable();
  }

  @Override
  public ImmutableGraph<N> asGraph() {
    return new ImmutableGraph<>(this); // safe because the view is effectively immutable
  }

  private static <N, V> ImmutableMap<N, GraphConnections<N, V>> getNodeConnections(
      ValueGraph<N, V> graph) {

 * graph.putEdgeValue("San Jose", "San Jose", 0.0);
 * graph.putEdgeValue("San Francisco", "San Jose", 48.4);
 *
 * // Building an immutable value graph
 * ImmutableValueGraph<String, Double> immutableGraph =
 *     ValueGraphBuilder.undirected()
 *         .allowsSelfLoops(true)
 *         .<String, Double>immutable()
 *         .putEdgeValue("San Francisco", "San Francisco", 0.0)

 * graph.putEdgeValue("San Jose", "San Jose", 0.0);
 * graph.putEdgeValue("San Francisco", "San Jose", 48.4);
 *
 * // Building an immutable value graph
 * ImmutableValueGraph<String, Double> immutableGraph =
 *     ValueGraphBuilder.undirected()
 *         .allowsSelfLoops(true)
 *         .<String, Double>immutable()
 *         .putEdgeValue("San Francisco", "San Francisco", 0.0)

    mutableNetwork.addNode("A");
    ImmutableNetwork<String, Integer> immutableNetwork = ImmutableNetwork.copyOf(mutableNetwork);

    assertThat(immutableNetwork.asGraph()).isInstanceOf(ImmutableGraph.class);
    assertThat(immutableNetwork).isNotInstanceOf(MutableNetwork.class);
    assertThat(immutableNetwork).isEqualTo(mutableNetwork);

    mutableNetwork.addNode("B");

   *
   * @since 33.1.0 (present with return type {@code Graph} since 20.0)
   */
  // TODO(b/31438252): Consider potential optimizations for this algorithm.
  public static <N> ImmutableGraph<N> transitiveClosure(Graph<N> graph) {
    ImmutableGraph.Builder<N> transitiveClosure =
        GraphBuilder.from(graph).allowsSelfLoops(true).<N>immutable();
    // Every node is, at a minimum, reachable from itself. Since the resulting transitive closure