return (result == null) ? cellSet = createCellSet() : result;
  }

  Set<Cell<R, C, V>> createCellSet() {
    return new CellSet();
  }

  abstract Iterator<Table.Cell<R, C, V>> cellIterator();

  Spliterator<Table.Cell<R, C, V>> cellSpliterator() {
    return Spliterators.spliterator(cellSet(), Spliterator.NONNULL | Spliterator.DISTINCT);
  }

  @WeakOuter

   */
  @Override
  public Set<Cell<R, C, V>> cellSet() {
    return super.cellSet();
  }

  @Override
  Iterator<Cell<R, C, V>> cellIterator() {
    return new CellIterator();
  }

  private final class CellIterator implements Iterator<Cell<R, C, V>> {
    final Iterator<Entry<R, Map<C, V>>> rowIterator = backingMap.entrySet().iterator();
    @Nullable Entry<R, Map<C, V>> rowEntry;

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

    @Override
    public Collection<V> values() {
      return original.values();
    }

    @Override
    Iterator<Cell<C, R, V>> cellIterator() {
      return Iterators.transform(original.cellSet().iterator(), Tables::transposeCell);
    }

    @Override
    @GwtIncompatible // Spliterator
    Spliterator<Cell<C, R, V>> cellSpliterator() {

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

    @Override
    public Collection<V> values() {
      return original.values();
    }

    @Override
    Iterator<Cell<C, R, V>> cellIterator() {
      return Iterators.transform(original.cellSet().iterator(), Tables::transposeCell);
    }
  }

  private static <

   */
  @Override
  public Set<Cell<R, C, @Nullable V>> cellSet() {
    return super.cellSet();
  }

  @Override
  Iterator<Cell<R, C, @Nullable V>> cellIterator() {
    return new AbstractIndexedListIterator<Cell<R, C, @Nullable V>>(size()) {
      @Override
      protected Cell<R, C, @Nullable V> get(int index) {
        return getCell(index);
      }
    };
  }