if (!(viewHandler instanceof AjaxViewHandler)) {
if(log.isDebugEnabled()){
log.debug("Set AjaxViewHandler on top of chain");
}
AjaxViewHandler ajaxViewHandler = new AjaxViewHandler(viewHandler);
ajaxViewHandler.fillChain(facesContext);
application.setViewHandler(ajaxViewHandler);
} else {
((AjaxViewHandler) viewHandler).fillChain(facesContext);
}