我想将assets/1.json替换为api URL，因为所需的数据在API中，而不是本地的，我该如何更改它，我已经尝试过了，但仍然出错。谢谢

static Future<Map<String, DataKuliahModel>> getDataKuliah() async {
    String url = Constant.baseURL;
    String token = await UtilSharedPreferences.getToken();
    await Future.delayed(const Duration(seconds: 4));
    // String responseJson = await rootBundle.loadString('assets/1.json');

    Map<String, DataKuliahModel> finalResult = {};
    final response = await http.get(
      Uri.parse(
        '$url/auth/mhs_siakad/perwalian/get_paket',
      ),
      headers: {
        'Authorization': 'Bearer $token',
      },
    );
    final result = jsonDecode(response)['data'] as Map<String, dynamic>;
    result.forEach((key, value) {
      DataKuliahModel dataKuliah = DataKuliahModel.fromMap(value);
      finalResult.addAll({
        key: dataKuliah,
      });
    });
    return finalResult;
  }