private ListUtil() {
    }
@Test
    public void testListUtil() {
        Assertions.assertNotNull(ListUtil.emptyIsDefault(Collections.emptyList(), Collections.singletonList(1)));
        Assertions.assertNotNull(ListUtil.findFirst(Collections.singletonList(1), res -> res == 1));
        Assertions.assertNull(ListUtil.findFirst(Collections.singletonList(1), res -> false));
        Assertions.assertNull(ListUtil.findFirst(Collections.emptyList(), res -> false));
    }