}

  @Override
  public boolean containsAll(Collection<?> targets) {
    for (Object target : targets) {
      if (target == null) {
        // This set never contains null.  We need to explicitly check here
        // because some comparator might throw NPE (e.g. the natural ordering).
        return false;
      }
    }
    try {
      return sortedDelegate.containsAll(targets);
    } catch (ClassCastException e) {

  }

  /**
   * A sensible implementation of {@link Multiset#elementSet} in terms of the following methods:
   * {@link ForwardingMultiset#clear}, {@link ForwardingMultiset#contains}, {@link
   * ForwardingMultiset#containsAll}, {@link ForwardingMultiset#count}, {@link
   * ForwardingMultiset#isEmpty}, the {@link Set#size} and {@link Set#iterator} methods of {@link

            return parent.add(e);
        }

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

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

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

    }

    @Override
    public boolean contains(@Nullable Object o) {
      return Maps.containsEntryImpl(delegate(), o);
    }

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

    @Override
    public boolean removeAll(Collection<?> c) {
      return standardRemoveAll(c);
    }

    @Override

    }

    @Override
    public boolean contains(@Nullable Object o) {
      return multiset().contains(o);
    }

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

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

    @Override
    public abstract Iterator<E> iterator();

    }

    @Override
    public boolean contains(@Nullable Object o) {
      return multiset().contains(o);
    }

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

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

    @Override
    public abstract Iterator<E> iterator();

            return parent.add(e);
        }

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

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

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

    }

    @Override
    public boolean contains(@Nullable Object o) {
      return Maps.containsEntryImpl(delegate(), o);
    }

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

    @Override
    public boolean removeAll(Collection<?> c) {
      return standardRemoveAll(c);
    }

    @Override

      synchronized (mutex) {
        return delegate().contains(o);
      }
    }

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

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

      synchronized (mutex) {
        return delegate().contains(o);
      }
    }

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

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