code: public static String getChecksum(String url, ResourceReaderHandler rsReader, JawrConfig jawrConfig)
  			throws IOException, ResourceNotFoundException {
  
  		String checksum = null;
  		InputStream is = null;
  
  		boolean generatedBinaryResource = jawrConfig.getGeneratorRegistry().isGeneratedBinaryResource(url);
  
  		try {
  
  			if (!generatedBinaryResource) {
  				url = PathNormalizer.asPath(url);
  			}
  
  			is = rsReader.getResourceAsStream(url);
  
  			if (is != null) {
  				checksum = CheckSumUtils.getChecksum(is, jawrConfig.getBinaryHashAlgorithm());
  			} else {
  				throw new ResourceNotFoundException(url);
  			}
  		} catch (FileNotFoundException e) {
  			throw new ResourceNotFoundException(url);
  		} finally {
  			IOUtils.close(is);
  		}
  
  		return checksum;
  	}
docs: Return the checksum of the path given in parameter, if the resource is
  not found, null will b returned.
  
  @param url
  the url path to the resource file
  @param rsReader
  the resource reader handler
  @param jawrConfig
  the jawrConfig
  @return checksum of the path given in parameter
  @throws IOException
  if an IO exception occurs.
  @throws ResourceNotFoundException
  if the resource is not found.