code: public TableCell getOrCreateCell(final int colIndex) {
          TableCell cell = this.cells.get(colIndex);
          if (cell == null) {
              cell = new TableCellImpl(this.writeUtil, this.xmlUtil, this.stylesContainer, this.dataStyles,
                      this.libreOfficeMode, this,
                      colIndex);
              this.cells.set(colIndex, cell);
          }
          return cell;
      }
docs: Get the cell at given index. If the cell was not created before, then it is created by this method.
  
  @param colIndex the index of the cell in the row
  @return a cell