object[] attributes = MyString.GetType().GetCustomAttributes(false);
                                    object[] newAttributes = new object[attributes.Length+1];
                                    for (int k = 0; k < attributes.Length; k++) newAttributes[k] = attributes[k];
                                    newAttributes[attributes.Length] = "hfghfgh";
                                    PropertyInfo pi =  MyString.GetType().GetProperty("CustomAttributes", BindingFlags.Public | BindingFlags.Instance);