return toArrayList(this).toArray(a);
    }
  }

  private static <E> ArrayList<E> toArrayList(Collection<E> c) {
    // Avoid calling ArrayList(Collection), which may call back into toArray.
    ArrayList<E> result = new ArrayList<>(c.size());
    Iterators.addAll(result, c.iterator());
    return result;
  }

  boolean removeIf(BiPredicate<? super K, ? super V> filter) {

   *       {@link #withoutCloser(AsyncFunction)}
   * </ul>
   *
   * <p>Example usage:
   *
   * <pre>{@code
   * // Fall back to a secondary input stream in case of IOException.
   * ClosingFuture<InputStream> inputFuture =
   *     firstInputFuture.catchingAsync(

      return toArrayList(this).toArray(a);
    }
  }

  private static <E> ArrayList<E> toArrayList(Collection<E> c) {
    // Avoid calling ArrayList(Collection), which may call back into toArray.
    ArrayList<E> result = new ArrayList<>(c.size());
    Iterators.addAll(result, c.iterator());
    return result;
  }

  final class KeySet extends AbstractCacheSet<K> {