VKAPI uploading photos to a group?

Question

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I want to upload photos to the server. But I don’t understand why the photos_list parameter is required if it is not specified in the documentation.

var VK = require('vksdk');
var unirest = require('unirest');

var vk = new VK({
   'appId'     : 5496471,
   'appSecret' : '******************',
   'language'  : 'ru'
});

vk.setToken('**********************');
vk.setSecureRequests(true);

vk.request('photos.getWallUploadServer', {'group_id' : 110234774}, function(data) {
  console.log(data); // Первый запрос
  unirest.post(data.response.upload_url)
  .headers({'Content-Type': 'multipart/form-data'})
  .attach('file1', 'photo.jpg') // Attachment
  .end(function (response) {
    console.log(response); // Второй запрос
    var resp = JSON.parse(response.body);

    var server = resp.server;
    var photo = JSON.stringify(resp.photo).replace(/\\/g,'');
    var hash = resp.hash;
    var gid = '110234774';

    vk.request('photos.saveWallPhoto', {'server' : server, 'photo': photo, 'hash':hash, 'group_id':gid}, function(data) {
      console.log(data);
      console.log(data); // Третий запрос
    });
  });

});

Answers:
First:

{ response: 
   { upload_url: 'http://cs633719.vk.com/upload.php?act=do_add&mid=366989513&aid=-14&gid=110234774&hash=cc1461536b7025867bca6f9369bbce1d&rhash=acd25af777118327539ab92ecb47b03e&swfupload=1&api=1&wallphoto=1',
     album_id: -14,
     user_id: 366989513 } }

Second:

{"server":633719,"photo":"[{\\"photo\\":\\"67c0e2babf:x\\",\\"sizes\\":,\\"kid\\":\\"5fbd02d96a77ac7583c441b06c50c0a4\\",\\"debug\\":\\"xsxmxxxoxpxqxrx\\"}]","hash":"035e981fb844ead49920dcbdb7f576a6"}

The third:

{ error: 
   { error_code: 100,
     error_msg: 'One of the parameters specified was missing or invalid: photos_list is invalid',
     request_params: 
      [ [Object],
        [Object],
        [Object],
        [Object],
        [Object],
        [Object],
        [Object],
        [Object],
        [Object] ] } }