private void CreateTree(List<GoodCategory> categories)
 {
     var groups = categories.GroupBy(x => x.Parent.Id).ToList();
     if (groups.Any())
     {
         foreach (IGrouping<int, GoodCategory> group in groups)
         {
             test.Add(group);
             var items = group.ToList();
             CreateTree(items);
         }
     }
 }