@Test
public void testHashCodeContract() {

    assertTrue("Wrong hashCode implementation, same objects have NOT same hash-code ", one.hashCode() == sameRefAsOne.hashCode());
    assertFalse("Wrong hashCode implementation, different objects have same hash-code", one.hashCode() == two.hashCode());
    assertTrue("Wrong hashCode implementation, same objects have NOT same hash-code ", one.hashCode() == sameAsOne.hashCode());
}