code: protected String getCurrentInterval(HttpServletRequest req, boolean saveToSession){
  		String intervalParameter = req.getParameter(PARAM_INTERVAL);
  		String interval = intervalParameter;
  		if (interval==null){
  			interval = (String)req.getSession().getAttribute(BEAN_INTERVAL);
  			if (interval == null)
  				interval = DEFAULT_INTERVAL;
  		}
  		if (intervalParameter!=null && saveToSession)
  			req.getSession().setAttribute(BEAN_INTERVAL, interval);
  		return interval;
  	}
docs: Returns the currently selected interval, either as parameter or from session.
  @param req
  @param saveToSession - if true the value from request will be stored to session.
  @return