code: public static List<UIUserSession> getUIUserSessions()
      {
          final List<UIUserSession> ret = new ArrayList<>();
          final Collection<UserSession> userSessions = RegistryManager.getUserSessions();
          for (final UserSession userSession : userSessions) {
              ret.add(new UIUserSession(userSession.getUserName(), userSession.getSessionId(), userSession
                              .getLastActivity()));
          }
          return ret;
      }
docs: Gets the UI user sessions.
  
  @return list of currently registered Users