FutureBuilder snapshot.hasData always return false

Question

i'm new to learning darts and flutter i'm making code to display data with FutureBuilder, in console window i got the response i want, but the snapshot.hashData code always returns false

Myclass model

class ResponseDataBarang {
  int? _kode;
  String? _pesan;
  List<Data>? _data;

  ResponseDataBarang({int? kode, String? pesan, List<Data>? data}) {
    if (kode != null) {
      this._kode = kode;
    }
    if (pesan != null) {
      this._pesan = pesan;
    }
    if (data != null) {
      this._data = data;
    }
  }

  int? get kode => _kode;
  set kode(int? kode) => _kode = kode;
  String? get pesan => _pesan;
  set pesan(String? pesan) => _pesan = pesan;
  List<Data>? get data => _data;
  set data(List<Data>? data) => _data = data;

  ResponseDataBarang.fromJson(Map<String, dynamic> json) {
    _kode = json['kode'];
    _pesan = json['pesan'];
    if (json['data'] != null) {
      _data = <Data>[];
      json['data'].forEach((v) {
        _data!.add(new Data.fromJson(v));
      });
    }
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['kode'] = this._kode;
    data['pesan'] = this._pesan;
    if (this._data != null) {
      data['data'] = this._data!.map((v) => v.toJson()).toList();
    }
    return data;
  }
}



class Data {
  String? _kdBrg;
  String? _nmBrg;

  Data(
      {String? kdBrg,
        String? nmBrg,
      }) {
    if (kdBrg != null) {
      _kdBrg = kdBrg;
    }
    if (nmBrg != null) {
      _nmBrg = nmBrg;
    }
  }

  String? get kdBrg => _kdBrg;
  set kdBrg(String? kdBrg) => _kdBrg = kdBrg;
  String? get nmBrg => _nmBrg;


  Data.fromJson(Map<String, dynamic> json) {
    _kdBrg = json['KdBrg'];
    _nmBrg = json['NmBrg'];

  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = Map<String, dynamic>();
    data['KdBrg'] = _kdBrg;
    data['NmBrg'] = _nmBrg;

    return data;
  }
}

My request

i am confused for the json format as generated what return value is suitable for my method request

Future<ResponseDataBarang> ambilDataBarang() async {

    Dio apiClient=ApiClient().init();
    final response=await apiClient.post('http://192.168.1.8/aplikasikasir/data_barang.php', data: FormData.fromMap(({
     "NmUser":"T",
    })));
    return ResponseDataBarang.fromJson(response.data);
  }
}

Response i got

{"kode":1,"pesan":"Data Tersedia","data":[{"KdBrg":"170164017","NmBrg":"ST PP HONGNIE SANDAL","Harga":"38000","Stock_Akhir":"0","Sat_1":"PT","Sat_2":"","Sat_3":"","Sat_4":"","Isi_2":"0","Isi_3":"0","Isi_4":"0","KdSupl":"","NmSupl":"","Ket1":""}]}