Java - Digitos que no estan en una lista

public class Digitos {

	/* */

	public static String testDigitos(List<Long> numbers) {

		String res = new String("0123456789");

		for(Long l : numbers) {

			for(char s : l.toString().toCharArray()) {

				res = res.replace(s, '\0');

			}

			if(res.isEmpty())

				break;

		}

		return res;

	}

	/* */

	public static void main(String[] args) {

		List<Long> test = Arrays.asList(321L, 95649L);

		System.out.println("Result: '" + testDigitos(test) + "'");

	}

}

public static String digitosQueNoEstanEn(List<Long> numeros) {

        List<String> numerosDel0Al9 = Arrays.stream("0123456789".split("")).collect(Collectors.toList());

        numeros.stream()

                .forEach((l) -> {

                    Arrays.stream(l.toString().split("")).collect(Collectors.toList()).stream()

                            .filter((b) -> (numerosDel0Al9.contains(b)))

                            .forEach((b) -> {

                                numerosDel0Al9.remove(b);

                            });

                });

        String strinNumeros = "";

        strinNumeros = numerosDel0Al9.stream()

                .reduce(strinNumeros, String::concat);

        return strinNumeros;

}