How to display the Numberformat info in GridSummaryColumn of WPF DataGrid (SfDataGrid)?

public class CustomCaptionSummaryCellRenderer : GridCaptionSummaryCellRenderer
{
    // Method to initialize the CaptionSummaryCell.
    public override void OnInitializeEditElement(DataColumnBase dataColumn, GridCaptionSummaryCell uiElement, object dataContext)
    {
        GridColumn column = dataColumn.GridColumn;
        if (dataContext is Group)
        {
            var groupRecord = dataContext as Group;
            if (this.DataGrid.CaptionSummaryRow == null)
            {
                // get the column which is grouped
                var groupedColumn = this.GetGroupedColumn(groupRecord);
                //set the captionsummarycell text as customized.
                uiElement.Content = GetCustomizedCaptionText(groupedColumn.HeaderText, groupRecord.Key,
                    groupRecord.ItemsCount);
            }
            else if (this.DataGrid.CaptionSummaryRow.ShowSummaryInRow)
            {
                uiElement.Content = SummaryCreator.GetSummaryDisplayTextForRow(groupRecord.SummaryDetails,
                    this.DataGrid.View);
            }
            else
                uiElement.Content = SummaryCreator.GetSummaryDisplayText(groupRecord.SummaryDetails,
                    column.MappingName, this.DataGrid.View);
        }
    }
 
    // Method to update the CaptionSummaryCell
    public override void OnUpdateEditBinding(DataColumnBase dataColumn, GridCaptionSummaryCell element, object dataContext)
    {
        GridColumn column = dataColumn.GridColumn;
 
        if (element.DataContext is Group && this.DataGrid.View.GroupDescriptions.Count > 0)
        {
            var groupRecord = element.DataContext as Group;
            //get the column which is grouped.
            var groupedColumn = this.GetGroupedColumn(groupRecord);
            if (this.DataGrid.CaptionSummaryRow == null)
            {
                if (this.DataGrid.View.GroupDescriptions.Count < groupRecord.Level)
                    return;
                //set the captionsummary text as customized.
                element.Content = GetCustomizedCaptionText(groupedColumn.HeaderText,       groupRecord.Key, groupRecord.ItemsCount);
            }
            else if (this.DataGrid.CaptionSummaryRow.ShowSummaryInRow)
            {
                element.Content = SummaryCreator.GetSummaryDisplayTextForRow(groupRecord.SummaryDetails,
                    this.DataGrid.View, groupedColumn.HeaderText);
            }
            else
                element.Content = SummaryCreator.GetSummaryDisplayText(groupRecord.SummaryDetails,
                    column.MappingName, this.DataGrid.View);
        }
    }
 
    // Method to get the Grouped Column.
    private GridColumn GetGroupedColumn(Group group)
    {
        var groupDesc = this.DataGrid.View.GroupDescriptions[group.Level - 1] as PropertyGroupDescription;
        foreach (var column in this.DataGrid.Columns)
        {
            if (column.MappingName == groupDesc.PropertyName)
            {
                return column;
            }
        }
        return null;
    }     
 
    // Method to Customize the CaptionSummaryCell Text.
    private string GetCustomizedCaptionText(string columnName, object groupName, int itemsCount)
    {
        //entryText - instead of "Items", the entryText is assigned to Customize the CaptionSummaryCell Text.
        groupName = GetNumberFormatInfo(groupName,columnName);
 
        string entryText = "Items";
        return string.Format("{0}: {1} - {2} {3}", columnName, groupName, itemsCount, entryText);
    }
 
    private string GetNumberFormatInfo(object value, string columnName)
    {
        if (columnName == "EmployeeSalary")
        {
            //based on the column name, you can set the NumberFormatInfo to the summary columns.
            var cultureName = CultureInfo.CurrentCulture.Name;
            NumberFormatInfo nfi = new CultureInfo(cultureName, false).NumberFormat;
            double formatedNumber = (double)value;
            nfi.NumberDecimalDigits = 4;
            int[] mySizes = { 2, 3, 0 };
            nfi.NumberGroupSizes = mySizes;
            nfi.NumberGroupSeparator = "*";
            nfi.NumberDecimalSeparator = "..";
 
            var content = formatedNumber.ToString("N", nfi);
            return content;
        }
        return value.ToString();
    }
}

protected override void OnAttached()
{
    //default CaptionSummaryCellRenderer is removed.            
    this.AssociatedObject.CellRenderers.Remove("CaptionSummary");
 
    //Customized CaptionSummaryCellRenderer is added.
    this.AssociatedObject.CellRenderers.Add("CaptionSummary", new CustomCaptionSummaryCellRenderer());
}