code: public synchronized void initialize() {
  
          List<I_CmsContextMenuItem> result = Lists.newArrayList();
          for (I_CmsContextMenuItemProvider provider : m_providerMap.values()) {
              result.addAll(provider.getMenuItems());
          }
          m_itemCache = result;
      }
docs: Initializes this instance.<p>
  
  This must be called after the provider classes have been added.