* of {@code Comparator} for pre-Java-8 users, in the same sense that {@link FluentIterable} is an
 * enriched {@link Iterable} for pre-Java-8 users.
 *
 * <h3>Three types of methods</h3>
 *
 * Like other fluent types, there are three types of methods present: methods for <i>acquiring</i>,
 * <i>chaining</i>, and <i>using</i>.
 *
 * <h4>Acquiring</h4>
 *
 * <p>The common ways to get an instance of {@code Ordering} are:

  static final ImmutableMap<Object, Object> EMPTY =
      new RegularImmutableMap<>(null, new Object[0], 0);

  /*
   * This is an implementation of ImmutableMap optimized especially for Android, which does not like
   * objects per entry.  Instead we use an open-addressed hash table.  This design is basically
   * equivalent to RegularImmutableSet, save that instead of having a hash table containing the

              "DelayedShutdownHook-for-" + service,
              new Runnable() {
                @Override
                public void run() {
                  try {
                    // We'd like to log progress and failures that may arise in the
                    // following code, but unfortunately the behavior of logging
                    // is undefined in shutdown hooks.

              && entryKey != null
              && map.keyEquivalence.equivalent(key, entryKey)) {
            // If the value disappeared, this entry is partially collected,
            // and we should pretend like it doesn't exist.
            V entryValue = e.getValue();
            if (entryValue == null) {
              if (isCollected(e)) {
                int newCount = this.count - 1;
                ++modCount;

   *
   * (Perhaps it should also have required that its cause was a RuntimeException. However, that
   * would have required that we throw a different kind of exception for wrapping *checked*
   * exceptions in methods like Futures.getUnchecked and LoadingCache.get.)
   */

  /**
   * Creates a new instance with {@code null} as its detail message and no cause.
   *

 * asynchronous operations. You can chain them together manually with calls to methods like {@link
 * Futures#transform(ListenableFuture, Function, Executor) Futures.transform}, but you will often
 * find it easier to use a framework. Frameworks automate the process, often adding features like
 * monitoring, debugging, and cancellation. Examples of frameworks include:
 *
 * <ul>

     *            {@link Severity#ERROR}.
     * @param version The version since the problem is relevant
     * @param source A hint about the source of the problem like a file path, may be {@code null}.
     * @param lineNumber The one-based index of the line containing the problem or {@code -1} if unknown.

                            prefix, "version", problems, errOn30, Version.V20, d.getVersion(), d.getManagementKey(), d);

                    /*
                     * TODO Extensions like Flex Mojos use custom scopes like "merged", "internal", "external", etc. In
                     * order to don't break backward-compat with those, only warn but don't error out.
                     */
                    validateEnum(

      return EndpointPair.ordered(endpoints.target(), endpoints.source());
    }
    return endpoints;
  }

  // NOTE: this should work as long as the delegate graph's implementation of edges() (like that of
  // AbstractGraph) derives its behavior from calling successors().
  private static class TransposedGraph<N> extends ForwardingGraph<N> {
    private final Graph<N> graph;

    TransposedGraph(Graph<N> graph) {

            return AbstractNetwork.this.edges().size();
          }

          // Mostly safe: We check contains(u) before calling successors(u), so we perform unsafe
          // operations only in weird cases like checking for an EndpointPair<ArrayList> in a
          // Network<LinkedList>.
          @SuppressWarnings("unchecked")
          @Override
          public boolean contains(@CheckForNull Object obj) {