docs: public CmsUser update(CmsObject cms, String siteRoot) {
  
          CmsUser originalUser = m_map.getIfPresent(siteRoot);
          if ((originalUser == null) || originalUser.equals(cms.getRequestContext().getCurrentUser())) {
              m_map.put(siteRoot, cms.getRequestContext().getCurrentUser());
              return null;
          }
          return originalUser;
      }