users might code the following in the composer:

  if (passAuthentication){
      Executions.getCurrent().sendRedirect("main.zul");
  }

We should consider 2 possible redirection.
1. redirect by Http response (response code 302, 303)
1.1 after request (both connect and au)
1.2 after do au
2. redirect by Au response. - have to pass au response and get au response command