* <p>In many cases, you may wish to override {@link #descendingMultiset()} to return an instance
   * of a subclass of {@code StandardDescendingMultiset}.
   */
  protected abstract class StandardDescendingMultiset extends DescendingMultiset<E> {
    /** Constructor for use by subclasses. */
    public StandardDescendingMultiset() {}

    @Override
    SortedMultiset<E> forwardMultiset() {
      return ForwardingSortedMultiset.this;
    }

   * of a subclass of {@code StandardDescendingMultiset}.
   *
   * @since 15.0
   */
  protected abstract class StandardDescendingMultiset extends DescendingMultiset<E> {
    /** Constructor for use by subclasses. */
    public StandardDescendingMultiset() {}

    @Override
    SortedMultiset<E> forwardMultiset() {

    }

    @Override
    protected SortedMultiset<E> delegate() {
      return backingMultiset;
    }

    @Override
    public SortedMultiset<E> descendingMultiset() {
      return new StandardDescendingMultiset() {

        @Override
        Iterator<Entry<E>> entryIterator() {
          return backingMultiset.descendingMultiset().entrySet().iterator();
        }
      };
    }

    @Override

    }

    @Override
    protected SortedMultiset<E> delegate() {
      return backingMultiset;
    }

    @Override
    public SortedMultiset<E> descendingMultiset() {
      return new StandardDescendingMultiset() {

        @Override
        Iterator<Entry<E>> entryIterator() {
          return backingMultiset.descendingMultiset().entrySet().iterator();
        }
      };
    }

    @Override