How to export groups to Excel and also export group Outlining from SfDataGrid?

using Syncfusion.UI.Xaml.Grid.Converter;
using Syncfusion.XlsIO;
 
private static void OnExecuteExportToExcel(object sender, ExecutedRoutedEventArgs args)
{
     var dataGrid = args.Source as SfDataGrid;
     if (dataGrid == null) return;
     try
     {
          // Creating an instance for ExcelExportingOptions which is passed as a parameter to the ExportToExcel method.
          ExcelExportingOptions options = new ExcelExportingOptions();
          options.AllowOutlining = true;
          // Exports Datagrid to Excel and returns ExcelEngine.
          var excelEngine = dataGrid.ExportToExcel(dataGrid.View, options);
          // Gets the exported workbook from the ExcelEngine.
          var workBook = excelEngine.Excel.Workbooks[0];
          // Saving the workbook.
          SaveFileDialog sfd = new SaveFileDialog
          {
               FilterIndex = 2,
               Filter = "Excel 97 to 2003 Files(*.xls)|*.xls|Excel 2007 to 2010 Files(*.xlsx)|*.xlsx"
          };
 
          if (sfd.ShowDialog() == true)
          {
               using (Stream stream = sfd.OpenFile())
               {
                    if (sfd.FilterIndex == 1)
                         workBook.Version = ExcelVersion.Excel97to2003;
                    else
                         workBook.Version = ExcelVersion.Excel2010;
                    workBook.SaveAs(stream);                        
               }
               //Launching the Excel file using the default Application.[MS Excel Or Free ExcelViewer]
               System.Diagnostics.Process.Start(sfd.FileName);
          }                                              
     }
}