@Override
    public Signer getSigner(SignerProviderContext context) {
        return awsClient.getSignerByURI(context.getUri());
    }
SQS alters the request endpoint as part of a request handler which inspects
the request's parameters.  As a result we must always look up the signer
by the resulting request URI.  This signer provider always does that lookup
instead of defaulting to a cached signer.
aws-java-sdk-sqs/src/main/java/com/amazonaws/services/sqs/internal/auth/SQSSignerProvider.java