code: public static void renderException(final Exception ex, final HttpServletResponse response) {
          val map = new HashMap<String, String>();
          map.put("error", ex.getMessage());
          map.put("stacktrace", Arrays.deepToString(ex.getStackTrace()));
          renderException(map, response);
      }
docs: Render exceptions. Adds error messages and the stack trace to the json model
  and sets the response status accordingly to note bad requests.
  
  @param ex       the ex
  @param response the response