var view = new ListCollectionView(propertylist);
using (view.DeferRefresh())
{
var gd = view.GroupDescriptions;
gd.Clear();
gd.Add(new PropertyGroupDescription("BuiltParameterGroupName"));
gd.Add(new PropertyGroupDescription("ParameterGroupOrderBy"));
var pgdParaGroup = gd[0] as PropertyGroupDescription;
pgdParaGroup.Converter = new MyGroupCellConverter();
C1FlexGrid1.GroupHeaderConverter = new GroupHeaderConverter();