如何在 Google 人 API 获取请求中设置 'personFields' 查询参数?

How can i set 'personFields' query parameter in Google People API get request?

  var xhttp = new XMLHttpRequest();
  var theUrl = "https://people.googleapis.com/v1/people/c3591871730916654475?personFields='names,photos,coverPhotos'";
  xhttp.open("GET", theUrl, true);
  xhttp.setRequestHeader('Authorization', 'Bearer ' + currentSessionAccessToken)
  xhttp.onload = function(){
    if(xhttp.status == 200){
        var profileJson = JSON.parse(xhttp.response);
        resolve(profileJson);     
    }
    else{
        if(xhttp.status == 404){
          resolve('No_RESULT_FOUND');
        }
        else{
        reject(xhttp.statusText);
      }
    }
  };
  xhttp.onerror = function(){
    reject(xhttp.statusText);
  };
  xhttp.send();

以上是我的 XMLHttpRequest。请求后我收到以下错误:

"{ "error":{ "code": 400, "message": "Invalid personFields mask path: \"\"names\"。有效路径记录在 https://developers.google.com/people/api/rest/v1/people/get 中。", "status": "INVALID_ARGUMENT" } } “

有人能给我推荐一条有效的路径吗?我没有在文档中找到。

personFields='names,photos,coverPhotos' 改为 personFields=names,photos,coverPhotos,去掉 '