docs: private static String b64SignHmacSha1(final String aAwsSecretKey, final String aCanonicalString)
              throws NoSuchAlgorithmException, InvalidKeyException {
          final SecretKeySpec signingKey = new SecretKeySpec(aAwsSecretKey.getBytes(), HASH_CODE);
          final Mac mac = Mac.getInstance(HASH_CODE);
  
          mac.init(signingKey);
  
          return new String(Base64.getEncoder().encode(mac.doFinal(aCanonicalString.getBytes())));
      }