code: public static int setSessionTimeout(final int interval)
  	{
  		final HttpSession session = getHttpSession();
  		if (session != null)
  		{
  			session.setMaxInactiveInterval(interval);
  			return interval;
  		}
  		return -1;
  	}
docs: Sets the given interval(in seconds) that will be set the session timeout.
  
  @param interval
  The number of seconds.
  
  @return the given interval(in seconds) or -1 if the {@link javax.servlet.http.HttpSession} is
  null.