code: @SuppressWarnings("unchecked")
      protected void expand(final boolean _expand)
      {
          try {
              // only if the element was opened the first time e.g. reload etc.
              if ((isRoot() || _expand)
                         && (Context.getThreadContext().containsSessionAttribute(getCacheKey()) || this.forceExpanded)) {
                  final Map<String, Boolean> sessMap = (Map<String, Boolean>) Context
                                  .getThreadContext().getSessionAttribute(getCacheKey());
                  for (final UIStructurBrowser uiChild : this.children) {
                      if (isForceExpanded() || sessMap == null || sessMap.containsKey(uiChild.getInstanceKey())) {
                          final Boolean expandedTmp = sessMap == null || isForceExpanded()
                                                  ? true : sessMap.get(uiChild.getInstanceKey());
                          if (expandedTmp != null && expandedTmp && uiChild.isParent()) {
                              uiChild.setExecutionStatus(UIStructurBrowser.ExecutionStatus.ADDCHILDREN);
                              final List<Return> ret = getObject4Event().executeEvents(EventType.UI_TABLE_EVALUATE,
                                                  ParameterValues.INSTANCE, uiChild.getInstance(),
                                                  ParameterValues.CLASS, uiChild);
                              final Map<Instance, Boolean> map = (Map<Instance, Boolean>) ret.get(0).get(
                                              ReturnValues.VALUES);
                              uiChild.setExpanded(true);
                              uiChild.add2ExpandedBrowsers(uiChild);
                              if (uiChild.getTableUUID() == null) {
                                  uiChild.executeTree(map, true);
                              } else {
                                  uiChild.executeTreeTable(map, true);
                              }
                          }
                      }
                  }
              }
          } catch (final EFapsException e) {
              UIStructurBrowser.LOG.error("Error retreiving Session info for StruturBrowser from Command with UUID: {}",
                              getCommandUUID(), e);
          }
      }
docs: Expand the tree with the information from the Session.
  @param _expand is this inside an expand