返回 HTML 而不是 JSON 的 Google Apps 脚本的内容服务

Trying out the Content Service API and the example is returning HTML when it should be returning JSON, what am I doing wrong?

https://developers.google.com/apps-script/guides/content

function doGet(request) {
  var events = CalendarApp.getEvents(
    new Date(Number(request.parameters.start) * 1000),
    new Date(Number(request.parameters.end) * 1000));
  var result = {
    available: events.length == 0
  };
  return ContentService.createTextOutput(JSON.stringify(result))
    .setMimeType(ContentService.MimeType.JSON);
}

来自另一个试图发出请求的文件的 GAS:

function myFunction() {
  var url = "published URL";
  url+="?start=1325437200&end=1325439000";

  var options = {
    method:"get"
  }
  var response = UrlFetchApp.fetch(url,options).getContentText();
  response = JSON.parse(response); //error, unexpected token <
}