code: private void deselectChildren(CmsTreeItem item) {
  
          for (String childId : m_childrens.get(item.getId())) {
              CmsTreeItem child = m_categories.get(childId);
              deselectChildren(child);
              child.getCheckBox().setChecked(false);
              if (m_selectedCategories.contains(childId)) {
                  m_selectedCategories.remove(childId);
              }
          }
      }
docs: Deselects all child items of the provided item.
  @param item the item for which all childs should be deselected.d