This Grails plugin solution works well in a test or local env because Same-Origin Policy will prevent you from implementing a front-end jQuery AJAX call since the domains are different.
In Prod, since HTTPS was used, and since the domains are the same, a jQuery AJAX call works much better then having the logic in the controller and using the REST plugin.
$.getJSON('${YOUR_URL}', function(data){ var yourData = data.yourData; //Operate on data here });