@Test public void testAddReverse() throws DogException { AdderUsageObserver.setUsed(false); Target source = new Target(); source.setPets(Arrays.asList(3L)); Source target = SourceTargetMapper.INSTANCE.toSource(source); assertThat(target).isNotNull(); assertThat(target.getPets().size()).isEqualTo(1); assertThat(target.getPets().get(0)).isEqualTo("cat"); }