docs: private void initPageData() {
  
          m_elementInstances = new HashMap<String, CmsContainerElementBean>();
          m_parentContainers = new HashMap<String, CmsContainerBean>();
          if (m_page != null) {
              for (CmsContainerBean container : m_page.getContainers().values()) {
                  for (CmsContainerElementBean element : container.getElements()) {
                      m_elementInstances.put(element.getInstanceId(), element);
                      m_parentContainers.put(element.getInstanceId(), container);
                      try {
                          if (element.isGroupContainer(m_cms) || element.isInheritedContainer(m_cms)) {
                              List<CmsContainerElementBean> children;
                              if (element.isGroupContainer(m_cms)) {
                                  children = CmsJspTagContainer.getGroupContainerElements(
                                      m_cms,
                                      element,
                                      m_request,
                                      container.getType());
                              } else {
                                  children = CmsJspTagContainer.getInheritedContainerElements(m_cms, element);
                              }
                              for (CmsContainerElementBean childElement : children) {
                                  m_elementInstances.put(childElement.getInstanceId(), childElement);
                                  m_parentContainers.put(childElement.getInstanceId(), container);
                              }
                          }
                      } catch (CmsException e) {
                          LOG.error(e.getLocalizedMessage(), e);
                      }
                  }
              }
              // also add detail only data
              if (m_detailOnlyPage != null) {
                  for (CmsContainerBean container : m_detailOnlyPage.getContainers().values()) {
                      for (CmsContainerElementBean element : container.getElements()) {
                          m_elementInstances.put(element.getInstanceId(), element);
                          m_parentContainers.put(element.getInstanceId(), container);
                      }
                  }
              }
          }
      }