问当我在节点js中创建post调用时，为什么Watson-conversation为任何请求返回相同的默认响应

EN

var express = require('express');
var conversationV1 = require('watson-developer-cloud/conversation/v1');
var bodyParser = require('body-parser');
var app = express();
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
    extended: false
}));
var conversation = new conversationV1({
    username: 'xxxxxx-1a06-4a90-xxxxx-xxxxxxxxxxx',
    password: 'xxxxxxxxxx',
    version_date: conversationV1.VERSION_DATE_2016_09_20
});
const updateMessage = (input, response) => {
    var responseText = null;
    if (!response.output) {
        response.output = {};
    } else {
        return response;
    }
    if (response.intents && response.intents[0]) {
        var intent = response.intents[0];
    if (intent.confidence >= 0.75) {
        responseText = 'I understood your intent was ' + intent.intent;
    } else if (intent.confidence >= 0.5) {
        responseText = 'I think your intent was ' + intent.intent;
    } else {
        responseText = 'I did not understand your intent';
    }
}
response.output.text = responseText;
return response;
};

app.post('/api/message', (req, res, next) => {
    const workspace = '254654de-2bfe-423a-92ec-6aa66620625a'; 
    if (!workspace || workspace === '<workspace-id>') {
        return res.json({
            output: {
                text: 'Please check the workspace'
            }
        });
    }
    const payload = {
        workspace_id: workspace,
        input: req.body.input || {},
        context: req.body.context || {}
    };

    // Send the input to the conversation service
    conversation.message(payload, (error, data) => {
        if (error) {
            return next(error);
        }
        return res.json(updateMessage(payload, data));
    });
});

app.listen(process.env.PORT || 3000);

exports.app = app