public class UniqueRandomNumberGeneratorImplV2 implements UniqueRandomNumberGenerator {

    private SecureRandom random;

    @Autowired
    public UniqueRandomNumberGeneratorImplV2(SecureRandom random) {
        this.random = random;
    }

    @Override
    public String generateRandomUnique(int length) {
        return IntStream.range(0, length)
                .mapToObj(i -> String.valueOf(random.nextInt(10)))
                .collect(Collectors.joining());
    }
}