public override void Sign(IRequest request, ClientConfig clientConfig, RequestMetrics metrics, string awsAccessKeyId, string awsSecretAccessKey)
{
var aws4Signer = SelectSigner(request, clientConfig) as AWS4Signer;
if (aws4Signer != null)
aws4Signer.Sign(request, clientConfig, metrics, awsAccessKeyId, awsSecretAccessKey);
else
SignRequest(request, clientConfig, metrics, awsAccessKeyId, awsSecretAccessKey);
}