How To Expand Or Collapse A Group On Double Click In WPF Sfdatagrid

//setting custom row generator to datagrid

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        this.dataGrid.RowGenerator = new CustomRowGenerator(this.dataGrid);
    }
}


//custom row generator

 public class CustomRowGenerator : RowGenerator
 {
     public CustomRowGenerator(SfDataGrid dataGrid)
         : base(dataGrid)
     {
     }

     protected override VirtualizingCellsControl GetVirtualizingCellsControl<T>()
     {
         if (typeof(T) == typeof(CaptionSummaryRowControl))
         {
             CustomCaptionSummaryRowControl rowcontrol = new CustomCaptionSummaryRowControl();
             rowcontrol.sfDataGrid = this.Owner;
             return rowcontrol;
         }
         return base.GetVirtualizingCellsControl<T>();
     }
 }


 //custom caption summary rowcontrol

  public class CustomCaptionSummaryRowControl : CaptionSummaryRowControl
 {
     public SfDataGrid sfDataGrid;

     public CustomCaptionSummaryRowControl()
         : base()
     {
         this.DefaultStyleKey = typeof(CustomCaptionSummaryRowControl);
     }

     protected override void OnPreviewMouseLeftButtonUp(MouseButtonEventArgs e)
     {
         var visualContainer = sfDataGrid.GetVisualContainer() as VisualContainer;
         var index = visualContainer.PointToCellRowColumnIndex(e.GetPosition(null));
         if (e.ClickCount == 1 && index.ColumnIndex != 0)
             return;
         base.OnPreviewMouseLeftButtonUp(e);
     }
     protected override void OnPreviewMouseDoubleClick(MouseButtonEventArgs e)
     {
         if (this.DataContext is Group)
         {
             var group = this.DataContext as Group;
             if (group.IsExpanded)
                 sfDataGrid.CollapseGroup(group);
             else
                 sfDataGrid.ExpandGroup(group);
         }
         base.OnPreviewMouseDoubleClick(e);
     }
 }