ContentItemGroupDefault childItem = newInstance(ContentItemGroupDefault.class);
childItem.setId("B");
childItem.setParentGroup(parentItem);
parentItem.addChildGroup(childItem);
ContentItemGroupDTO resultChild = mapper.map(childItem, ContentItemGroupDTO.class);
assertNotNull(resultChild);
assertEquals("B", resultChild.getId());
assertNull(resultChild.getChildGroups());
ContentItemGroupDTO parentResult = resultChild.getParentGroup();
assertEquals("A", parentResult.getId());
assertTrue(parentResult.getChildGroups().contains(resultChild));
}