code: private void addOuToTree(CmsOrganizationalUnit ou, CmsOrganizationalUnit parent_ou) {
  
          Item containerItem;
          containerItem = m_treeContainer.addItem(ou);
          if (containerItem == null) {
              containerItem = getItem(ou);
          }
          containerItem.getItemProperty(PROP_NAME).setValue(getIconCaptionHTML(ou, CmsOuTreeType.OU));
          containerItem.getItemProperty(PROP_TYPE).setValue(CmsOuTreeType.OU);
          m_treeContainer.setParent(ou, parent_ou);
      }
docs: Adds an ou to the tree.<p>
  
  @param ou to be added
  @param parent_ou parent ou