Javascript AWS Lambda上未定义节点表示请求正文

Im使用AWS Amplify生成Node Express rest API端点

我最近添加了一个新的端点，但我一直在请求主体中未定义，我无法确定我可能错过了在哪里配置我的应用程序

App.js

var express = require("express");
var bodyParser = require("body-parser");
var awsServerlessExpressMiddleware = require("aws-serverless-express/middleware");

// declare a new express app
var app = express();
app.use(bodyParser.urlencoded({extended:false}));
app.use(bodyParser.json());
app.use(awsServerlessExpressMiddleware.eventContext());

// Enable CORS for all methods
app.use(function(req, res, next) {
  res.header("Access-Control-Allow-Origin", "*");
  res.header(
    "Access-Control-Allow-Headers",
    "Origin, X-Requested-With, Content-Type, Accept"
  );
  next();
});

var aws = require("aws-sdk");
const https = require("https");

app.post("/refresh", function(req, res){
    console.log(JSON.stringify(req.body));
    // {}
    console.log(JSON.parse(req.body));
    //Error: unexpected token o in JSON at position 1
}); 

我正在AWS控制台上用这个负载测试这个

{
  "path": "/refresh",
  "httpMethod": "POST",
  "header": "{\"content-Type\":\"application/json\"}",
  "body": "{\"Username\":\"test\"}"
}

将标题设置为

"Content-Type: application/json"

将标题设置为

"Content-Type: application/json"