Cell thisCell = sumRow.createCell(colIndex);
String sumTargetArea = new CellReference(3, colIndex, true, true).formatAsString() + ":" + new CellReference(rowIndex -1, colIndex, true, true).formatAsString();
Cell thisCell = sumRow.createCell(colIndex);
String sumTargetArea = new CellReference(3, colIndex, true, true).formatAsString() + ":" + new CellReference(rowIndex -1, colIndex, true, true).formatAsString();