@Override
    public boolean add(E element) {
        return add(element, element.hashCode());
    }
@Test
    public void testIsEmpty() {
        final OAHashSet<Integer> set = new OAHashSet<>(8);
        assertTrue("Set should be empty", set.isEmpty());

        set.add(1);
        assertFalse("Set should not be empty", set.isEmpty());
    }