docs: public CmsContainerPageBean removeModelGroupContainers(CmsContainerPageBean page) {
  
          Map<String, List<CmsContainerBean>> containersByParent = getContainerByParent(page);
          Set<String> modelInstances = new HashSet<String>();
          for (CmsContainerElementBean element : page.getElements()) {
              if (element.getIndividualSettings().containsKey(CmsContainerElement.MODEL_GROUP_ID)) {
                  modelInstances.add(element.getInstanceId());
              }
          }
  
          Set<String> descendingInstances = new HashSet<String>();
          for (String modelInstance : modelInstances) {
              descendingInstances.addAll(collectDescendingInstances(modelInstance, containersByParent));
          }
          List<CmsContainerBean> containers = new ArrayList<CmsContainerBean>();
          for (CmsContainerBean container : page.getContainers().values()) {
              if ((container.getParentInstanceId() == null)
                  || !descendingInstances.contains(container.getParentInstanceId())) {
                  // iterate the container elements to replace the model group elements
                  List<CmsContainerElementBean> elements = new ArrayList<CmsContainerElementBean>();
                  for (CmsContainerElementBean element : container.getElements()) {
                      if (modelInstances.contains(element.getInstanceId())) {
                          CmsUUID modelId = new CmsUUID(
                              element.getIndividualSettings().get(CmsContainerElement.MODEL_GROUP_ID));
                          CmsContainerElementBean replacer = new CmsContainerElementBean(
                              modelId,
                              element.getFormatterId(),
                              element.getIndividualSettings(),
                              false);
                          elements.add(replacer);
                      } else {
                          elements.add(element);
                      }
                  }
                  containers.add(
                      new CmsContainerBean(
                          container.getName(),
                          container.getType(),
                          container.getParentInstanceId(),
                          container.isRootContainer(),
                          container.getMaxElements(),
                          elements));
  
              }
          }
          return new CmsContainerPageBean(containers);
      }