code: public String toRangeAddress(final int row1, final int col1, final int row2, final int col2) {
          return this.toCellAddress(row1, col1) + ":" + this.toCellAddress(row2, col2);
      }
docs: Return the Excel/OO/LO address of a range
  
  @param row1 the first row
  @param col1 the first col
  @param row2 the last row
  @param col2 the last col
  @return the Excel/OO/LO address