无法使用Dialogfow获得Webhook实现响应

Question

我正在使用具有webhook实现（操作和参数）的Dialog流来调用外部API并解析数据，并应返回到我的dialogflow代理。在这里，我无法将我的回复返回到dialogflow操作。

我的示例代码：

"use strict";

const express = require("express");
const bodyParser = require("body-parser");
const http = require('https');
const https = require("https");
var request = require("request")
var result;


const restService = express();

restService.use(
  bodyParser.urlencoded({
    extended: true
  })
);

restService.use(bodyParser.json());

restService.post('/v2/webhook',(req,res)=>{

 var response = "currently service is unable to process your request"; 
 console.log(req.body)
 //console.log(req.body.result.action)

  if(!req.body || !req.body.queryResult|| !req.body.queryResult.action){  

   response = "Action is missing in request";
   console.log(response)
    //console.log(req.body.result.action)

}else{

  var action = req.body.queryResult.action;

 if(action === 'input.welcome'){
    response = "Hi Welcome to my test agent helper intent!";
    console.log(response)
 }
  else if(action === 'ask.for.sign.in'){  

 //Calling my test API
 callAddressApi().then((output) => {
     res.setHeader('Content-Type', 'application/json'); 
     res.send(JSON.stringify({ 'fulfillmentText': output }));   
    }).catch(() => {     
     res.send(JSON.stringify({ 'fulfillmentText': 'I dont know the address...!' }));
    });  


 }
}

var speech={
         "fulfillmentText":response
        ,"fulfillmentMessages":[
            {
                "text": {
                    "text": [
                        response
                    ]
                }
            }
        ]
        ,"source":"webhook-echo-sample"
    } 

  return res.json(speech);
});

function callAddressApi () {
  return new Promise((resolve, reject) => {
    // Create the path for the HTTP request to get the address
    let path = "https://maps.googleapis.com/maps/api/geocode/json?address=london";  

    // Make the HTTP request to get the weather
    http.get({path: path}, (res) => {
      let body = ''; // var to store the response chunks
      res.on('data', (d) => { body += d; }); // store each response chunk
      res.on('end', () => {
        // After all the data has been received parse the JSON for desired data
        let respnse = JSON.parse(body);
        let address = respnse['results']['0'][0]['formatted_address'];  
    console.log(address);

        // Create response
        let output = address;

        result = output;

        // Resolve the promise with the output text
        console.log(output);
        resolve(output);
      });
      res.on('error', (error) => {
        console.log(`Error calling the address API: ${error}`)
        reject();
      });
    });
  });

}


restService.listen(process.env.PORT || 8000, function() {
  console.log("Server up and listening");
});

//代码结尾。

任何人都可以评论并告诉我我错了吗？谢谢。