public void AddItem(HoSoDoAn hoso, string yKien)
        {
            CartLine line = lineCollection.Where(p => p.HoSo.id == hoso.id).FirstOrDefault();

            if (line == null)
            {
                lineCollection.Add(new CartLine {
                    HoSo = hoso, yKien = yKien
                });
            }
            else
            {
                line.yKien += "\n" + yKien;
            }
        }
 public void RemoveLine(HoSoDoAn hoso)
 {
     lineCollection.RemoveAll(l => l.HoSo.id == hoso.id);
 }