docs: public static String pdfTagAction(ServletRequest request, String file, int width, int height, String format)
      throws CmsException {
  
          CmsFlexController controller = CmsFlexController.getController(request);
          CmsObject cms = controller.getCmsObject();
          CmsResource pdfRes = cms.readResource(file);
          CmsPdfThumbnailLink linkObj = new CmsPdfThumbnailLink(cms, pdfRes, width, height, format);
          return linkObj.getLinkWithOptions();
      }