internal void Add(ItemTypeMap map)
 {
     foreach (XmlElementAttribute attribute in map.SerializerAttributes)
     {
         Add(attribute);
     }
 }
        public static void RegisterTypes(ItemTypeMap types)
        {
            if (types == null)
            {
                throw new ArgumentNullException("types");
            }

            TypeMap.Add(types);
            RegisterSerializer();
        }