* element). Note that for an {@link Object#equals}-based multiset, this gives the same result as
   * {@link Collections#frequency} (which would presumably perform more poorly).
   *
   * <p><b>Note:</b> the utility method {@link Iterables#frequency} generalizes this operation; it
   * correctly delegates to this method when dealing with a multiset, but it can also accept any

   * MoreExecutors#directExecutor}. Otherwise, avoid it: See the warnings on the docs for {@code
   * directExecutor}.
   *
   * <p>This is the most general listener interface. For common operations performed using
   * listeners, see {@link Futures}. For a simplified but general listener interface, see {@link
   * Futures#addCallback addCallback()}.
   *

#       options in "$@", and eventually passing that to Java.
#
#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
#       see the in-line comments for details.
#
#       There are tweaks for specific operating systems such as AIX, CygWin,
#       Darwin, MinGW, and NonStop.
#

   * MoreExecutors#directExecutor}. Otherwise, avoid it: See the warnings on the docs for {@code
   * directExecutor}.
   *
   * <p>This is the most general listener interface. For common operations performed using
   * listeners, see {@link Futures}. For a simplified but general listener interface, see {@link
   * Futures#addCallback addCallback()}.
   *

   * href="https://url.spec.whatwg.org/#application-x-www-form-urlencoded-percent-encode-set">URL
   * form parameter names and values</a>. Escaping is performed with the UTF-8 character encoding.
   * The caller is responsible for <a
   * href="https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#multipart-form-data">replacing

          }

          @Override
          public int size() {
            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

          }

          @Override
          public int size() {
            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

    awaitDone(
        new FinalizationPredicate() {
          @Override
          public boolean isDone() {
            return ref.get() == null;
          }
        });
  }

  /**
   * Tries to perform a "full" garbage collection cycle (including processing of weak references and
   * invocation of finalize methods) and waits for it to complete. Ensures that at least one weak

  @SuppressWarnings("unchecked")
  static final ImmutableMap<Object, Object> EMPTY =
      new RegularImmutableMap<>((Entry<Object, Object>[]) ImmutableMap.EMPTY_ENTRY_ARRAY, null, 0);

  /**
   * Closed addressing tends to perform well even with high load factors. Being conservative here
   * ensures that the table is still likely to be relatively sparse (hence it misses fast) while
   * saving space.
   */

@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public abstract class FluentIterable<E extends @Nullable Object> implements Iterable<E> {
  // We store 'iterable' and use it instead of 'this' to allow Iterables to perform instanceof
  // checks on the _original_ iterable when FluentIterable.from is used.
  // To avoid a self retain cycle under j2objc, we store Optional.absent() instead of