Create Nested Groups in Excel in Java

import com.spire.xls.*;

import java.awt.*;

public class CreateNestedGroup {

    public static void main(String[] args) {

        //Create a Workbook object
        Workbook workbook = new Workbook();

        //Get the first worksheet
        Worksheet sheet = workbook.getWorksheets().get(0);

        //Create a cell style
        CellStyle style = workbook.getStyles().addStyle("style");
        style.getFont().setColor(Color.blue);
        style.getFont().isBold(true);

        //Write data to cells
        sheet.get("A1").setValue("Project plan for project X");
        sheet.get("A1").setCellStyleName(style.getName());
        sheet.get("A3").setValue("Set up");
        sheet.get("A3").setCellStyleName(style.getName());
        sheet.get("A4").setValue("Task 1");
        sheet.get("A5").setValue("Task 2");
        sheet.getCellRange("A4:A5").borderAround(LineStyleType.Thin);
        sheet.getCellRange("A4:A5").borderInside(LineStyleType.Thin);
        sheet.get("A7").setValue("Launch");
        sheet.get("A7").setCellStyleName(style.getName());
        sheet.get("A8").setValue("Task 1");
        sheet.get("A9").setValue("Task 2");
        sheet.getCellRange("A8:A9").borderAround(LineStyleType.Thin);
        sheet.getCellRange("A8:A9").borderInside(LineStyleType.Thin);

        //Pass false to isSummaryRowBelow method , which indicates the summary rows appear above detail rows
        sheet.getPageSetup().isSummaryRowBelow(false);

        //Group the rows using groupByRows method
        sheet.groupByRows(2,9,false);
        sheet.groupByRows(4,5,false);
        sheet.groupByRows(8,9,false);

        //Save to file
        workbook.saveToFile("NestedGroup.xlsx", ExcelVersion.Version2016);
    }
}