private static object OnCoerceSortMemberPath(DependencyObject d, object baseValue)
        {
            var column         = (DataGridPactComboBoxColumn)d;
            var sortMemberPath = (string)baseValue;

            if (string.IsNullOrEmpty(sortMemberPath))
            {
                sortMemberPath = DataGridHelper.GetPathFromBinding(column.EffectiveBinding as Binding);
            }

            return(sortMemberPath);
        }