MutableNetwork<Integer, Object> network =
          networkBuilder.allowsParallelEdges(true).allowsSelfLoops(true).build();

      assertThat(network.nodes()).isEmpty();
      assertThat(network.edges()).isEmpty();
      AbstractNetworkTest.validateNetwork(network);

      while (network.nodes().size() < NUM_NODES) {
        network.addNode(gen.nextInt(NODE_POOL_SIZE));
      }

    protected static final String ACCESS_CONTROL_ALLOW_METHODS = "Access-Control-Allow-Methods";

    protected static final String ACCESS_CONTROL_ALLOW_PRIVATE_NETWORK = "Access-Control-Allow-Private-Network";

    protected static final String ACCESS_CONTROL_ALLOW_CREDENTIALS = "Access-Control-Allow-Credentials";

    protected static final String ACCESS_CONTROL_MAX_AGE = "Access-Control-Max-Age";

   *             cancelled the {@code Future}.
   *       </ol>
   *       Given all these possibilities, it is frequently possible for listeners to execute in UI
   *       threads, RPC network threads, or other latency-sensitive threads. In those cases, slow
   *       listeners can harm responsiveness, slow the system as a whole, or worse. (See also the
   *       note about locking below.)

      MutableNetwork<Integer, Object> network =
          networkBuilder.allowsParallelEdges(true).allowsSelfLoops(true).build();

      assertThat(network.nodes()).isEmpty();
      assertThat(network.edges()).isEmpty();
      AbstractNetworkTest.validateNetwork(network);

      while (network.nodes().size() < NUM_NODES) {
        network.addNode(gen.nextInt(NODE_POOL_SIZE));
      }

  /**
   * Returns a view of {@code network} with the direction (if any) of every edge reversed. All other
   * properties remain intact, and further updates to {@code network} will be reflected in the view.
   */
  public static <N, E> Network<N, E> transpose(Network<N, E> network) {
    if (!network.isDirected()) {
      return network; // the transpose of an undirected network is an identical network
    }

    return Maps.asMap(network.edges(), network::incidentNodes);
  }

  /**
   * The HTTP <a href="https://wicg.github.io/private-network-access/#headers">{@code
   * Access-Control-Allow-Private-Network}</a> header field name.
   *
   * @since 31.1
   */
  public static final String ACCESS_CONTROL_ALLOW_PRIVATE_NETWORK =
      "Access-Control-Allow-Private-Network";
  /** The HTTP {@code Access-Control-Allow-Credentials} header field name. */