code: public void updateTimeServer(String timeServer, Boolean useTimeServer) throws PageException {
  	checkWriteAccess();
  	if (useTimeServer != null && useTimeServer.booleanValue() && !StringUtil.isEmpty(timeServer, true)) {
  	    try {
  		new NtpClient(timeServer).getOffset();
  	    }
  	    catch (IOException e) {
  		try {
  		    new NtpClient(timeServer).getOffset();
  		}
  		catch (IOException ee) {
  		    throw Caster.toPageException(ee);
  		}
  	    }
  	}
  
  	boolean hasAccess = ConfigWebUtil.hasAccess(config, SecurityManager.TYPE_SETTING);
  	if (!hasAccess) throw new SecurityException("no access to update regional setting");
  
  	Element scope = _getRootElement("regional");
  	scope.setAttribute("timeserver", timeServer.trim());
  	if (useTimeServer != null) scope.setAttribute("use-timeserver", Caster.toString(useTimeServer));
  	else scope.removeAttribute("use-timeserver");
      }
docs: update the timeServer
  
  @param timeServer
  @param useTimeServer
  @throws PageException