code: public List<CmsSessionInfo> getSessionInfos(CmsUUID userId) {
  
          // since this method could be called from another thread
          // we have to prevent access before initialization
          if (m_sessionStorageProvider == null) {
              return Collections.emptyList();
          }
          return m_sessionStorageProvider.getAllOfUser(userId);
      }
docs: Returns a list of all active session info objects for the specified user.<p>
  
  An OpenCms user can have many active sessions.
  This is e.g. possible when two people have logged in to the system using the
  same username. Even one person can have multiple sessions if he
  is logged in to OpenCms with several browser windows at the same time.<p>
  
  @param userId the id of the user
  
  @return a list of all active session info objects for the specified user