public static int findFreePort() {
        int portUsed;
        do {
            portUsed = PORT.getAndIncrement();
        } while (!available(portUsed));
        return portUsed;
    }

    private static boolean available(int port) {
        try (Socket ignored = new Socket("localhost", port)) {
            return false;
        } catch (IOException ignored) {
            return true;
        }
    }