}

        public boolean removeAll(final Collection<?> c) {
            return parent.removeAll(c);
        }

        public boolean retainAll(final Collection<?> c) {
            return parent.retainAll(c);
        }

        public void clear() {
            parent.clear();
        }

        public boolean equals(final Object o) {
            return parent.equals(o);

   * Multiset)}.
   *
   * <p>This method refines {@link Collection#retainAll} to further specify that it <b>may not</b>
   * throw an exception in response to any of {@code elements} being null or of the wrong type.
   *
   * @see Multisets#retainOccurrences(Multiset, Multiset)
   */
  @CanIgnoreReturnValue
  @Override
  boolean retainAll(Collection<?> c);

  /**
   * {@inheritDoc}
   *

      synchronized (mutex) {
        return delegate().removeAll(c);
      }
    }

    @Override
    public boolean retainAll(Collection<?> c) {
      synchronized (mutex) {
        return delegate().retainAll(c);
      }
    }

    @Override
    public int size() {
      synchronized (mutex) {
        return delegate().size();
      }
    }

      synchronized (mutex) {
        return delegate().removeAll(c);
      }
    }

    @Override
    public boolean retainAll(Collection<?> c) {
      synchronized (mutex) {
        return delegate().retainAll(c);
      }
    }

    @Override
    public boolean removeIf(Predicate<? super E> filter) {
      synchronized (mutex) {

    SortedSet<String> subset = elementSet.subSet("b", "f");
    assertThat(subset).containsExactly("b", "c", "d", "e").inOrder();

    assertTrue(subset.retainAll(asList("a", "c")));
    assertThat(elementSet).containsExactly("a", "c", "f").inOrder();
    assertThat(subset).containsExactly("c");
    assertEquals(5, ms.size());
  }

  public void testElementSetSubsetClear() {

    }
    if (intersect(features, requirements.getAbsentFeatures())) {
      if (logger.isLoggable(FINER)) {
        Set<Feature<?>> unwantedFeatures = copyToSet(requirements.getAbsentFeatures());
        unwantedFeatures.retainAll(features);
        logger.finer(
            Platform.format(
                "%s: skipping because these features are present: %s", method, unwantedFeatures));
      }
      return false;
    }

  public static <E extends @Nullable Object> Collection<E> filter(
      Collection<E> unfiltered, Predicate<? super E> predicate) {
    if (unfiltered instanceof FilteredCollection) {
      // Support clear(), removeAll(), and retainAll() when filtering a filtered
      // collection.
      return ((FilteredCollection<E>) unfiltered).createCombined(predicate);
    }

    return new FilteredCollection<>(checkNotNull(unfiltered), checkNotNull(predicate));

   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  public final boolean retainAll(Collection<?> elementsToKeep) {
    throw new UnsupportedOperationException();
  }

  /**
   * Guaranteed to throw an exception and leave the collection unmodified.
   *

   * @param elementsToRetain the elements to retain
   * @return {@code true} if any element was removed from {@code iterator}
   */
  @CanIgnoreReturnValue
  public static boolean retainAll(Iterator<?> removeFrom, Collection<?> elementsToRetain) {
    checkNotNull(elementsToRetain);
    boolean result = false;
    while (removeFrom.hasNext()) {
      if (!elementsToRetain.contains(removeFrom.next())) {

	if !ok {
		tillStr, ok = meta[AmzObjectLockRetainUntilDate]
	}
	if ok {
		if t, e := amztime.ISO8601Parse(tillStr); e == nil {
			retainTill = RetentionDate{t.UTC()}
		}
	}
	return ObjectRetention{XMLNS: "http://s3.amazonaws.com/doc/2006-03-01/", Mode: mode, RetainUntilDate: retainTill}
}

// GetObjectLegalHoldMeta constructs ObjectLegalHold from metadata
func GetObjectLegalHoldMeta(meta map[string]string) ObjectLegalHold {