Google云端硬盘SDK不会返回评论的selfLink字段

Question

对于我使用API​​请求的任何评论（甚至是文档内的示例），selfLink字段都缺失：

 { 
 "kind": "drive#comment",
 "commentId": "AAAAAF8FAJI",
 "createdDate": "2013-05-08T12:59:49.090Z",
 "modifiedDate": "2013-05-08T12:59:49.090Z",
 "author": {
  "kind": "drive#user",
  "displayName": "XXX",
  "picture": {
   "url": "//photo.jpg"
  },
  "isAuthenticatedUser": false
 },
 "htmlContent": "XXXX",
 "deleted": false,
 "status": "open",
 "context": {
  "type": "text/html",
  "value": "Some context"
 },
 "anchor": "kix.5hi345vj8mn5",
 "fileId": "sP98Rdx5lB7nbcNL6XD6msg",
 "fileTitle": "XXXX",
 "replies": [
 ]
}

然而，这里有记录：https://developers.google.com/drive/v2/reference/comments