Can't add cookie anymore in request.jar

I use request.js in a project, and since the version 2.30.0, I can't do that anymore:

var j = request.jar();
var cookie = request.cookie('uid');
cookie.value = browser.cookies.select({name:'uid'})[0].value;
j.add(cookie);

My error is:

 TypeError: Object #<CookieJar> has no method 'add'

Someone had the problem and solved it?