在dart (List<List<Tuple2>>)中序列化/反序列化嵌套的Tuple2数组的最佳方法是什么

import 'dart:convert';

void main() {
  List<List<Tuple2>> nestedList = [
    [Tuple2('A', 1), Tuple2('B', 2)],
    [Tuple2('C', 3), Tuple2('D', 4)]
  ];

  String jsonStr = jsonEncode(nestedList);
  print(jsonStr);
}

import 'dart:convert';

void main() {
  String jsonStr = '[[{"item1":"A","item2":1},{"item1":"B","item2":2}],'
      '[{"item1":"C","item2":3},{"item1":"D","item2":4}]]';

  dynamic json = jsonDecode(jsonStr);
  List<List<Tuple2>> nestedList = json.map<List<Tuple2>>(
    (list) => list.map<Tuple2>(
      (item) => Tuple2(item['item1'], item['item2'])
    ).toList()
  ).toList();

  print(nestedList);
}