code: public static void sendError(HttpServletRequest request, HttpServletResponse response, int status, String message) throws IOException {
  		if(request.getAttribute(IS_INCLUDED_REQUEST_ATTRIBUTE_NAME) == null) {
  			// Not included, sendError directly
  			if(message == null) {
  				response.sendError(status);
  			} else {
  				response.sendError(status, message);
  			}
  		} else {
  			// Is included, set attributes so top level tag can perform actual sendError call
  			request.setAttribute(STATUS_REQUEST_ATTRIBUTE_NAME, status);
  			request.setAttribute(MESSAGE_REQUEST_ATTRIBUTE_NAME, message);
  		}
  	}
docs: Sends an error.  When not in an included page, calls sendError directly.
  When inside of an include will set request attribute so outermost include can call sendError.