Restbrowser does not show optional attributes / required parameters anymore

On http://www.demo.onehippo.com/rest/browser you can choose between Top products or Product detail. The calls work, the result is shown in the Rest Call Output window.
But there used to be two dropdowns: Optional parameters for the Top products and Required parameters for the Product detail. Both are there in the html, but both are hidden after the page is loaded. Please restore this functionality.