code: 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();
      }
docs: The implementation of the tag.<p>
  
  @param request the current request
  @param file the path to the PDF
  @param width the thumbnail width
  @param height the thumbnail height
  @param format the image format
  
  @throws CmsException if something goes wrong
  
  @return the link to the PDF thumbnail