HipChatClient for Google Apps Script

hipchat.js

/**
 * HipChat client for Google Apps Script.
 * This code is based on node-hipchat https://github.com/nkohari/node-hipchat/blob/master/lib/hipchat.js
 */
 
(function(global) {
  var HipChatClient = (function () {
    HipChatClient.prototype.host = 'api.hipchat.com';
    
    function HipChatClient(apikey) {
      this.apikey = apikey;
      this.rateLimits = {
        limit: 0,
        remaining: 0,
        reset: 0
      };
    }
    
    HipChatClient.prototype._querystringify = function (obj) {
      var qs = '';
      for (var key in obj) {
        if (qs !== '') {
          qs += '&';
        }
        qs += (key + '=' + obj[key]);
      }
      return qs;
    };
    
    HipChatClient.prototype.postMessage = function(params) {
      var data, options, _ref, _ref1, _ref2;
      data = {
        room_id: params.room_id,
        from: (_ref = params.from) != null ? _ref : 'gas-hipchat',
        message: params.message,
        notify: params.notify ? 1 : 0,
        color: (_ref1 = params.color) != null ? _ref1 : 'yellow',
        message_format: (_ref2 = params.message_format) != null ? _ref2 : 'html'
      };
      options = this._prepareOptions({
        method: 'post',
        path: '/v1/rooms/message',
        data: data
      });
      return this._sendRequest(options);
    };
        
    HipChatClient.prototype._prepareOptions = function (op) {
      op.host = this.host;
      if (op.query == null) {
        op.query = {};
      }
      op.query['auth_token'] = this.apikey;
      op.query = this._querystringify(op.query);
      op.path += '?' + op.query;
      if (op.method === 'post' && (op.data != null)) {
        op.payload = this._querystringify(op.data);
        if (op.headers == null) {
          op.headers = {};
        }
      }
      op.url = op.host + op.path;
      return op;
    };
    
    HipChatClient.prototype._sendRequest = function(options) {
      var res = UrlFetchApp.fetch(options.url, options);
      if (res.getResponseCode() === 200) {
        return JSON.parse(res.getContentText());
      } else {
        Logger.log(res.getContentText());
        return null;
      }
    };    
       
    return HipChatClient;
  })();

  global.HipChatClient = HipChatClient;
})(this);

/**
 * Create HipChatClient
 *
 * <h3>Usage</h3>
 * <pre>
 * var hipchat = HipChatClient.create('your-api-key');
 * hipchat.postMessage({ room_id: 'xx', message: 'yy' });
 * </pre>
 * @param {string} apikey
 */
function create(apikey) {
  return new HipChatClient(apikey);
}

I can't get around this error: "Request failed for https://api.hipchat.com/v2/room/message?auth_token=mytokenishere returned code 405. Truncated server response: { "error": { "code": 405, "message": "

The method is not allowed for the requested URL.

", "type": "Method Not Allowed" } } (use muteHttpExceptions option to examine full response)"

Any ideas?