code: private static String generateSharedAccessSignatureHashHelper(String stringToSign, final StorageCredentials creds)
              throws StorageException, InvalidKeyException {
          
          Utility.assertNotNull("credentials", creds);
      
          Logger.debug(null, LogConstants.SIGNING, stringToSign);
  
          stringToSign = Utility.safeDecode(stringToSign);
          final String signature = StorageCredentialsHelper.computeHmac256(creds, stringToSign);
  
          Logger.verbose(null, LogConstants.SIGNING, stringToSign);
          
          return signature;
      }
docs: Get the signature hash embedded inside the Shared Access Signature.
  
  @param stringToSign
  The string to decode and hash
  @param creds
  Reference to the {@link StorageCredentials.}.
  
  @return The signature hash embedded inside the Shared Access Signature.
  
  @throws InvalidKeyException
  @throws StorageException