code: private String addCacheBuster(String url, BinaryResourcesHandler binaryRsHandler) throws IOException {
  
  		if (binaryRsHandler != null) {
  			FilePathMappingUtils.buildFilePathMapping(bundle, url, binaryRsHandler.getRsReaderHandler());
  		}
  
  		// Try to retrieve the cache busted URL from the bundle processing cache
  		String newUrl = null;
  		if (binaryMapping != null) {
  			newUrl = binaryMapping.get(url);
  			if (newUrl != null) {
  				return newUrl;
  			}
  		}
  
  		// Try to retrieve the from the image resource handler cache
  		if (binaryRsHandler != null) {
  			newUrl = binaryRsHandler.getCacheUrl(url);
  			if (newUrl != null) {
  				return newUrl;
  			}
  			// Retrieve the new URL with the cache prefix
  			try {
  				newUrl = CheckSumUtils.getCacheBustedUrl(url, binaryRsHandler.getRsReaderHandler(),
  						binaryRsHandler.getConfig());
  			} catch (ResourceNotFoundException e) {
  				LOGGER.info("Impossible to define the checksum for the resource '" + url + "'. ");
  				return url;
  			} catch (IOException e) {
  				LOGGER.info("Impossible to define the checksum for the resource '" + url + "'.");
  				return url;
  			}
  
  			binaryRsHandler.addMapping(url, newUrl);
  
  		} else {
  			newUrl = url;
  		}
  
  		binaryMapping.put(url, newUrl);
  
  		return newUrl;
  	}
docs: Adds the cache buster to the CSS image
  
  @param url
  the URL of the image
  @param binaryRsHandler
  the binary resource handler
  @return the url of the CSS image with a cache buster
  @throws IOException
  if an IO exception occurs