PersistableWithIdClass s1 = idClassRepository.save(new PersistableWithIdClass(1L, 1L));
PersistableWithIdClass s2 = idClassRepository.save(new PersistableWithIdClass(2L, 2L));
assertThat(idClassRepository.exists(s1.getId()), is(true));
assertThat(idClassRepository.exists(s2.getId()), is(true));
assertThat(idClassRepository.exists(new PersistableWithIdClassPK(1L, 2L)), is(false));
}