private static byte[] sha256(byte[] bytes) {
         try {
            MessageDigest md = MessageDigest.getInstance("SHA-256");
            md.update(bytes);
            return md.digest();
         }
         catch (NoSuchAlgorithmException e) {
             throw new UnsupportedOperationException(e.getMessage(), e);
         }
    }
Task 4.
<a href="https://docs.aws.amazon.com/general/latest/gr/sigv4-add-signature-to-request.html">Add the Signing Information to the Request</a>
src/main/java/io/fabric8/maven/docker/access/ecr/AwsSigner4.java