code: public void setColumnsSpanned(final int colIndex, final int n) {
          if (n <= 1) return;
  
          final TableCell firstCell = this.getOrCreateCell(colIndex);
          if (firstCell.isCovered()) // already spanned
              return;
  
          firstCell.markColumnsSpanned(n);
          this.coverRightCells(colIndex, n);
      }
docs: Add a span across columns
  
  @param colIndex the index of the first column
  @param n        the number of columns in the span