code: public static void drop(HttpExchange req) throws IOException {
  		setStandardHeaders(req);
  		req.sendResponseHeaders(418, 0);
  		try (OutputStream body = req.getResponseBody()) {
  			body.write(("apdu4j/"+SCTool.getVersion()).getBytes(StandardCharsets.UTF_8));
  		}
  	}
docs: Everything that is not 200 is considered as bad request.