code: @Test public void should_validate_entity_constrained_on_class() throws Exception {
    Long id=RandomUtils.nextLong();
    EntityWithClassLevelConstraint entity=new EntityWithClassLevelConstraint();
    entity.setId(id);
    entity.setFirstname("firstname");
    entity.setLastname("lastname");
    manager.persist(entity);
    EntityWithClassLevelConstraint found=manager.find(EntityWithClassLevelConstraint.class,id);
    assertThat(found).isNotNull();
    assertThat(found.getFirstname()).isEqualTo("firstname");
    assertThat(found.getLastname()).isEqualTo("lastname");
  }
  