* guids are randomly generated, we cannot compare them with '<' '>'
* we used to generate them this way: generator.generateTimeBasedUUID().toString()
* but now we generate them as java.util.UUID.randomUUID().toString()
*/
assertTrue(g1.compareTo(g3) != 0);
assertTrue(g3.compareTo(g1) != 0);
assertTrue(g3.compareTo(g2) != 0);
// when the groupId is not Comparable, the creation time is used as fallback
g1 = new EventGroup(new Object());
// sleep a mini bit to ensure that both event groups do not accidentially have the same