public static int shakeUp(String string, int upperLimit) {
        if (upperLimit < 1) {
            throw new IllegalArgumentException("upper limit must be greater than 0");
        }
        if (string == null) {
            return 0;
        }
        return (string.hashCode() & Integer.MAX_VALUE) % upperLimit;
    }
@Test
    void testShakeUp() {
        assertEquals(0, UtilsAndCommons.shakeUp(null, 1));
        char[] chars = new char[] {2325, 9, 30, 12, 2};
        assertEquals(0, UtilsAndCommons.shakeUp(new String(chars), 1));
    }