return Arrays.asList(contents).contains(object);
  }

  @Override
  public boolean containsAll(Collection<?> collection) {
    if (!allowNulls) {
      for (Object object : collection) {
        // behave badly
        if (object == null) {
          throw new NullPointerException();
        }
      }
    }
    return super.containsAll(collection);
  }

  @Override
  public Iterator<E> iterator() {

    SortedSet<String> set = of("a", "b", "f");
    assertTrue(set.containsAll(Collections.emptyList()));
    assertTrue(set.containsAll(asList("b")));
    assertTrue(set.containsAll(asList("b", "b")));
    assertTrue(set.containsAll(asList("b", "f")));
    assertTrue(set.containsAll(asList("b", "f", "a")));
    assertFalse(set.containsAll(asList("d")));
    assertFalse(set.containsAll(asList("z")));
    assertFalse(set.containsAll(asList("b", "d")));

    Range<Integer> range = Range.closed(3, 5);
    assertTrue(range.containsAll(asList(3, 3, 4, 5)));
    assertFalse(range.containsAll(asList(3, 3, 4, 5, 6)));

    // We happen to know that natural-order sorted sets use a different code
    // path, so we test that separately
    assertTrue(range.containsAll(ImmutableSortedSet.of(3, 3, 4, 5)));
    assertTrue(range.containsAll(ImmutableSortedSet.of(3)));

    return delegate.contains(object);
  }

  @Override
  public boolean containsAll(Collection<?> collection) {
    if (collection instanceof ImmutableEnumSet<?>) {
      collection = ((ImmutableEnumSet<?>) collection).delegate;
    }
    return delegate.containsAll(collection);
  }

  @Override
  public boolean isEmpty() {
    return delegate.isEmpty();
  }

  @CollectionSize.Require(absent = ZERO)
  public void testContainsAllMultisetIgnoresFrequency() {
    assertTrue(getMultiset().containsAll(getSubjectGenerator().create(e0(), e0(), e0())));
  }

  @CollectionSize.Require(absent = ZERO)
  public void testContainsAllListIgnoresFrequency() {
    assertTrue(getMultiset().containsAll(Arrays.asList(e0(), e0(), e0())));
  }

    SortedSet<String> set = of("a", "b", "f");
    assertTrue(set.containsAll(Collections.emptyList()));
    assertTrue(set.containsAll(asList("b")));
    assertTrue(set.containsAll(asList("b", "b")));
    assertTrue(set.containsAll(asList("b", "f")));
    assertTrue(set.containsAll(asList("b", "f", "a")));
    assertFalse(set.containsAll(asList("d")));
    assertFalse(set.containsAll(asList("z")));
    assertFalse(set.containsAll(asList("b", "d")));

  }

  @Override
  public boolean contains(@Nullable Object object) {
    return object != null && delegate.contains(object);
  }

  @Override
  public boolean containsAll(Collection<?> targets) {
    return delegate.containsAll(targets);
  }

  public int size() {
    return delegate.size();
  }

  @Override
  public boolean isEmpty() {
    return delegate.isEmpty();
  }

  @Override

    return comparator;
  }

  @Override
  public boolean contains(Object object) {
    return delegate.contains(checkValid(object));
  }

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

  @Override
  public Iterator<E> descendingIterator() {
    return delegate.descendingIterator();
  }

  @Override
  public NavigableSet<E> descendingSet() {

        }

        @Override
        public boolean remove(final Object o) {
            return parent.remove(o);
        }

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

        @Override
        public boolean addAll(final Collection<? extends E> c) {
            return parent.addAll(c);
        }

        @Override

    public boolean add(E element) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.add(element);
    }

    @Override
    public boolean containsAll(Collection<?> collection) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.containsAll(collection);
    }

    @Override
    public boolean addAll(Collection<? extends E> collection) {
      assertTrue(Thread.holdsLock(mutex));