assertFalse(violations.isEmpty());
    }

    // Test validation with groups
    public void test_validationGroups() {
        GroupTestBean bean = new GroupTestBean();
        bean.setDefaultCron("invalid");
        bean.setSpecialCron("invalid");

        // Validate default group
        Set<ConstraintViolation<GroupTestBean>> violations = validator.validate(bean, Default.class);