public static ComparisonChain start() {
    return ACTIVE;
  }

  private static final ComparisonChain ACTIVE =
      new ComparisonChain() {
        @SuppressWarnings("unchecked") // unsafe; see discussion on supertype
        @Override
        public ComparisonChain compare(Comparable<?> left, Comparable<?> right) {
          return classify(((Comparable<Object>) left).compareTo(right));
        }

    checkNotNull(valueComparator);
    return Comparator.<Optional<T>, @Nullable T>comparing(
        o -> orElseNull(o), Comparator.nullsLast(valueComparator));
  }

  // For discussion of why this exists, see the Android flavor.
  private static <T> @Nullable T orElseNull(Optional<T> optional) {
    return optional.orElse(null);
  }

  /**

  }

  public <T> void testWhere_mapFromBoundedWildcard() {
    Type subtype = new TypeCapture<TypedKeyMap<T>>() {}.capture();
    // TODO(benyu): This should check equality to an expected value, see discussion in cl/98674873
    Type unused =
        new TypeResolver()
            .where(
                new TypeCapture<Map<Integer, T>>() {}.capture(),

   * execute. If execution has already begun, the listener is executed immediately.
   *
   * <p>When selecting an executor, note that {@code directExecutor} is dangerous in some cases. See
   * the discussion in the {@link ListenableFuture#addListener ListenableFuture.addListener}
   * documentation.
   */
  public void add(Runnable runnable, Executor executor) {

      this.left = null;
      this.right = null;
    }

    /** Constructor for the header node. */
    AvlNode() {
      this.elem = null;
      this.elemCount = 1;
    }

    // For discussion of pred() and succ(), see the comment on the pred and succ fields.

    private AvlNode<E> pred() {
      return requireNonNull(pred);
    }

    private AvlNode<E> succ() {
      return requireNonNull(succ);

    @ParametricNullness
    public V setValue(@ParametricNullness V value) {
      updateIndex();
      if (index == ABSENT) {
        HashBiMap.this.put(key, value);
        return unsafeNull(); // See the discussion in getValue().
      }
      /*
       * The cast is safe because updateIndex found the entry for this key. (If it hadn't, then we

      if (delegate != null) {
        return uncheckedCastNullableTToT(delegate.put(key, value)); // See discussion in getValue().
      }
      updateLastKnownIndex();
      if (lastKnownIndex == -1) {
        put(key, value);
        return unsafeNull(); // See discussion in getValue().
      } else {
        V old = value(lastKnownIndex);
        CompactHashMap.this.setValue(lastKnownIndex, value);

   *
   * <p>Cancelling the pipeline will not cancel {@code future}, so that the pipeline can access its
   * value in order to close it.
   *
   * @param future the future to create the {@code ClosingFuture} from. For discussion of the
   *     future's result type {@code C}, see {@link DeferredCloser#eventuallyClose(Object,
   *     Executor)}.
   * @param closingExecutor the future's result will be closed on this executor

      if (delegate != null) {
        return uncheckedCastNullableTToT(delegate.put(key, value)); // See discussion in getValue().
      }
      updateLastKnownIndex();
      if (lastKnownIndex == -1) {
        put(key, value);
        return unsafeNull(); // See discussion in getValue().
      } else {
        V old = value(lastKnownIndex);
        CompactHashMap.this.setValue(lastKnownIndex, value);

  void invalidate(@CompatibleWith("K") Object key);

  /**
   * Discards any cached values for keys {@code keys}.
   *
   * @since 11.0
   */
  // For discussion of <? extends Object>, see getAllPresent.
  void invalidateAll(Iterable<? extends Object> keys);

  /** Discards all entries in the cache. */
  void invalidateAll();