code: private void validationFailed(FacesContext context) {
          Map<Object, Object> callbackParams = (Map<Object, Object>) context.getAttributes().get("CALLBACK_PARAMS");
          if(callbackParams == null) {
              callbackParams = new HashMap<>();
              callbackParams.put("CALLBACK_PARAMS",callbackParams);
          }
          callbackParams.put("validationFailed",true);
  
      }
docs: Set primefaces validationFailled callback param