docs: public void encodeEnd(FacesContext facesContext, UIComponent component)
          throws IOException
      {   
          renderInput(facesContext, component);
          
          if(!facesContext.isProjectStage(ProjectStage.Production) 
                && facesContext.isPostback() &&
               (facesContext.getPartialViewContext().isPartialRequest() ||
                facesContext.getPartialViewContext().isAjaxRequest()))
          {
              FormInfo formInfo = _ComponentUtils.findNestingForm(component, facesContext);
              if (formInfo != null && formInfo.getForm() instanceof HtmlForm)
              {
                  HtmlForm form = (HtmlForm) formInfo.getForm();
                  String content = form.getEnctype();
                  if(content==null || !content.contains("multipart/form-data"))
                  {
                       //Add facemessage
                       FacesMessage message = new FacesMessage("file upload requires a form with"+
                              " enctype equal to multipart/form-data");
                       facesContext.addMessage(component.getClientId(), message);
                  }
              }
          }
      }