code: protected function renderMarkup(FileUpload $element)
      {
          $markup = '
  <div class="%s" id="%s-dropzone">
      %s
     __input__
  </div>';
          
          return sprintf(
              $markup,
              $this->getDropZoneClass($element),
              $element->getAttribute('id'),
              $this->renderFileList($element)
          );
      }
docs: Renders the markup for the file upload element.
  
  @param FileUpload $element
  
  @return string