code: public void onPageEvent(long officialTime) {
  		//cleanup expired sessions
  		ArrayList garbage = new ArrayList(sessionsMirror.size());
  		Iterator i;
  		StandardSession session;
  		synchronized (sessionsMirror) {
  			i = sessionsMirror.values().iterator();
  			while (i.hasNext()) {
  				session = (StandardSession) i.next();
  				if (session.isExpired()) {
  					garbage.add(session);
  				}
  			}
  		}
  		i = garbage.iterator();
  		while (i.hasNext()) {
  			session = (StandardSession) i.next();
  			System.out.println(new LogEntry("session " + session.getToken() + " expired..."));
  			this.destroySessionByToken(session.getToken());
  		}
  	}
docs: Cleans up expired sessions.
  
  @param officialTime