docs: private Set<String> collectDescendingInstances(
          String instanceId,
          Map<String, List<CmsContainerBean>> containersByParent) {
  
          Set<String> descendingInstances = new HashSet<String>();
          descendingInstances.add(instanceId);
          if (containersByParent.containsKey(instanceId)) {
              for (CmsContainerBean container : containersByParent.get(instanceId)) {
                  for (CmsContainerElementBean element : container.getElements()) {
                      descendingInstances.addAll(collectDescendingInstances(element.getInstanceId(), containersByParent));
                  }
              }
          }
          return descendingInstances;
      }