如何从对话流聊天机器人获取响应并检测其意图？

Question

如何在第118行上修复此代码，该代码在Agent Package下找不到会话。 我尝试搜索视频及其文档，但没有找到。 这是代码的github链接：https://github.com/ypelud/chatbot.git

    import 'package:flutter/material.dart';
    import 'package:googleapis/dialogflow/v2.dart';
    import 'package:googleapis_auth/auth_io.dart';
    import 'package:flutter/services.dart';


    void main() => runApp(new MyApp());

    class MyApp extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
        return new MaterialApp(
        title: 'Neuralve',
        theme: new ThemeData(
            primarySwatch: Colors.brown,
        ),
        home: new ChatMessages(),
        );
    }
    }

    class ChatMessages extends StatefulWidget {
    @override
    _ChatMessagesState createState() => _ChatMessagesState();
    }

    class _ChatMessagesState extends State<ChatMessages>
        with TickerProviderStateMixin {
    List<ChatMessage> _messages = List<ChatMessage>();
    bool _isComposing = false;

    TextEditingController _controllerText = new TextEditingController();

    DialogflowApi _dialog;

    @override
    void initState() {
        super.initState();
        _initChatbot();
    }

    @override
    Widget build(BuildContext context) {
        return Scaffold(
            appBar: new AppBar(title: new Text("Neuralve")),
            body: Column(
            children: <Widget>[
                _buildList(),
                Divider(height: 8.0, color: Theme.of(context).accentColor),
                _buildComposer()
            ],
            ));
    }

    _buildList() {
        return Flexible(
        child: ListView.builder(
            padding: EdgeInsets.all(8.0),
            reverse: true,
            itemCount: _messages.length,
            itemBuilder: (_, index) {
                return Container(child: ChatMessageListItem(_messages[index]));
            }),
        );
    }

    _buildComposer() {
        return Container(
        margin: EdgeInsets.symmetric(horizontal: 8.0),
        child: Row(
            children: <Widget>[
            Flexible(
                child: TextField(
                controller: _controllerText,
                onChanged: (value) {
                    setState(() {
                    _isComposing = _controllerText.text.length > 0;
                    });
                },
                onSubmitted: _handleSubmit,
                decoration: InputDecoration.collapsed(hintText: "Send Message ..."),
                ),
            ),
            new IconButton(
                icon: Icon(Icons.send),
                onPressed:
                _isComposing ? () => _handleSubmit(_controllerText.text) : null,
            ),
            ],
        ),
        );
    }

    _handleSubmit(String value) {
        _controllerText.clear();
        _addMessage(
        text: value,
        name: "John Doe",
        initials: "DJ",
        );

        _requestChatBot(value);
    }

    _requestChatBot(String text) async {
        var dialogSessionId = "projects/chatbot-gdg/agent/sessions/ChatbotGDG";

        Map data = {
        "queryInput": {
            "text": {
            "text": text,
            "languageCode": "en",
            }
        }
        };

        var request = GoogleCloudDialogflowV2DetectIntentRequest.fromJson(data);
        var resp = await _dialog.projects.agent.sessions.detectIntent(request, dialogSessionId);

        var result = resp.queryResult;
        _addMessage(
            name: "Chat Bot",
            initials: "CB",
            bot: true,
            text: result.fulfillmentText);
    }

    void _initChatbot() async {
        String configString = await rootBundle.loadString('config/dialogflow.json');
        String _dialogFlowConfig = configString;

        var credentials = new ServiceAccountCredentials.fromJson(_dialogFlowConfig);

        const _SCOPES = const [DialogflowApi.CloudPlatformScope];

        var httpClient = await clientViaServiceAccount(credentials, _SCOPES);
        _dialog = new DialogflowApi(httpClient);
    }

    void _addMessage(
        {String name, String initials, bool bot = false, String text}) {
        var animationController = AnimationController(
        duration: new Duration(milliseconds: 700),
        vsync: this,
        );

        var message = ChatMessage(
            name: name,
            text: text,
            initials: initials,
            bot: bot,
            animationController: animationController);

        setState(() {
        _messages.insert(0, message);
        });

        animationController.forward();
    }
    }

    class ChatMessage {
    final String name;
    final String initials;
    final String text;
    final bool bot;

    AnimationController animationController;

    ChatMessage(
        {this.name,
            this.initials,
            this.text,
            this.bot = false,
            this.animationController});
    }

    class ChatMessageListItem extends StatelessWidget {
    final ChatMessage chatMessage;

    ChatMessageListItem(this.chatMessage);

    @override
    Widget build(BuildContext context) {
        return SizeTransition(
        sizeFactor: CurvedAnimation(
            parent: chatMessage.animationController, curve: Curves.easeOut),
        child: Container(
            margin: EdgeInsets.symmetric(vertical: 8.0),
            child: Row(
            children: <Widget>[
                Padding(
                padding: const EdgeInsets.only(left: 16.0),
                child: CircleAvatar(
                    child: Text(chatMessage.initials ?? "JD"),
                    backgroundColor: chatMessage.bot
                        ? Theme.of(context).accentColor
                        : Theme.of(context).highlightColor,
                ),
                ),
                Flexible(
                child: Container(
                    margin: EdgeInsets.only(left: 16.0),
                    child: new Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: <Widget>[
                        Text(chatMessage.name ?? "Jane Doe",
                            style: Theme.of(context).textTheme.subhead),
                        Container(
                        margin: const EdgeInsets.only(top: 5.0),
                        child: Text(chatMessage.text)
                        )
                    ],
                    ))
                )
            ],
            ),
        ),
        );
    }
    }

我曾尝试查找代理下的会话功能，但找不到它。