public void sign(SignableRequest<?> request, AWSCredentials credentials)
            throws SdkClientException {
        sign(request, SignatureVersion.V2, SigningAlgorithm.HmacSHA256, credentials);
    }
This signer will add "Signature" parameter to the request. Default
signature version is "2" and default signing algorithm is "HmacSHA256".

AWSAccessKeyId SignatureVersion SignatureMethod Timestamp Signature

@param request
           request to be signed.
@param credentials
           The credentials used to use to sign the request.
aws-java-sdk-core/src/main/java/com/amazonaws/auth/QueryStringSigner.java