final byte[] task3(AwsSigner4Request sr, AuthConfig credentials) {
        return hmacSha256(getSigningKey(sr, credentials), task2(sr));
    }
Task 3.
<a href="https://docs.aws.amazon.com/general/latest/gr/sigv4-create-string-to-sign.html">Calculate the Signature for AWS Signature Version 4</a>
src/main/java/io/fabric8/maven/docker/access/ecr/AwsSigner4.java