* Specifies that each value (not key) stored in the map should be wrapped in a {@link
   * WeakReference} (by default, strong references are used).
   *
   * <p>Weak values will be garbage collected once they are weakly reachable. This makes them a poor
   * candidate for caching.
   *
   * <p><b>Warning:</b> when this method is used, the resulting map will use identity ({@code ==})

   *
   * <p>In an undirected network, this is equivalent to {@link #adjacentNodes(Object)}.
   *
   * <p>This is <i>not</i> the same as "all nodes reachable from {@code node} by following outgoing
   * edges". For that functionality, see {@link Graphs#reachableNodes(Graph, Object)}.
   *
   * <p>If {@code node} is removed from the network after this method is called, the {@code Set}

 *       ImmutableList#subList} may retain a reference to the entire data set, preventing it from
 *       being garbage collected. If some of the data is no longer reachable through other means,
 *       this constitutes a memory leak. Pass the view collection to the appropriate {@code copyOf}
 *       method to obtain a correctly-sized copy.

 *       ImmutableList#subList} may retain a reference to the entire data set, preventing it from
 *       being garbage collected. If some of the data is no longer reachable through other means,
 *       this constitutes a memory leak. Pass the view collection to the appropriate {@code copyOf}
 *       method to obtain a correctly-sized copy.

  /* application types */
  /**
   * As described in <a href="http://www.ietf.org/rfc/rfc3023.txt">RFC 3023</a>, this constant
   * ({@code application/xml}) is used for XML documents that are "unreadable by casual users."
   * {@link #XML_UTF_8} is provided for documents that may be read by users.
   *
   * @since 14.0
   */

   * Specifies that each value (not key) stored in the cache should be wrapped in a {@link
   * WeakReference} (by default, strong references are used).
   *
   * <p>Weak values will be garbage collected once they are weakly reachable. This makes them a poor
   * candidate for caching; consider {@link #softValues} instead.
   *
   * <p><b>Note:</b> when this method is used, the resulting cache will use identity ({@code ==})

    ```java
    client.setConnectionSpecs(Arrays.asList(
        ConnectionSpec.MODERN_TLS, ConnectionSpec.COMPATIBLE_TLS));
    ```

 *  **New cipher suites.** Please confirm that your webservers are reachable
    with this limited set of cipher suites.

    ```
                                             Android
    Name                                     Version

    TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256  5.0

   */
  private static final SuccessorsFunction<Character> CYCLIC_GRAPH_CONTAINING_TREE =
      createDirectedGraph("ab", "bc", "bd", "ed", "ef", "fe");

  /**
   * A graph that is not a tree (for example, {@code h} is reachable from {@code f} via both {@code
   * e} and {@code g}) but is a valid input to {@link Traverser#forTree} when starting e.g. at node
   * {@code a} (all edges are directed facing downwards):
   *
   * {@snippet :

   */
  private static final SuccessorsFunction<Character> CYCLIC_GRAPH_CONTAINING_TREE =
      createDirectedGraph("ab", "bc", "bd", "ed", "ef", "fe");

  /**
   * A graph that is not a tree (for example, {@code h} is reachable from {@code f} via both {@code
   * e} and {@code g}) but is a valid input to {@link Traverser#forTree} when starting e.g. at node
   * {@code a} (all edges are directed facing downwards):
   *
   * {@snippet :

  /* application types */
  /**
   * As described in <a href="http://www.ietf.org/rfc/rfc3023.txt">RFC 3023</a>, this constant
   * ({@code application/xml}) is used for XML documents that are "unreadable by casual users."
   * {@link #XML_UTF_8} is provided for documents that may be read by users.
   *
   * @since 14.0
   */