code: @Override
      public Iterator<Cell> iterator()
      {
          if (cells != null)
          {
              return cells.iterator();
          }
          else // if (pbRow != null)
          {
              assert pbRow != null;
  
              return ConvertibleIteratorUtils.iterateAsCell(pbRow.getCellsList().iterator(),
                      // if there is no ColumnDescription what else we could do with that?
                      pbColumnDescriptions == null ?  Collections.emptyIterator() : pbColumnDescriptions.iterator());
          }
      }
docs: An iterator of the Cells in this row.
  @return an iterator.