* #iterator} to forward to this implementation.
   *
   * @since 7.0
   */
  protected Iterator<E> standardIterator() {
    return Multisets.iteratorImpl(this);
  }

  /**
   * A sensible, albeit inefficient, definition of {@link #size} in terms of {@link #entrySet}. If
   * you override {@link #entrySet}, you may wish to override {@link #size} to forward to this

        setCount(prevEntry.getElement(), 0);
        prevEntry = null;
      }
    };
  }

  @Override
  public Iterator<E> iterator() {
    return Multisets.iteratorImpl(this);
  }

  @Override
  public SortedMultiset<E> headMultiset(@ParametricNullness E upperBound, BoundType boundType) {
    return new TreeMultiset<>(
        rootReference,