private String arnRegion(Arn arn) {
        String region = arn.getRegion();
        if (region == null) {
            throw new IllegalArgumentException("Region is missing from ARN: " + arn);
        }
        return region;
    }
It should redirect signer if the request is CreateBucketRequest or ListRegionalBucketsRequest with outpostId present
aws-java-sdk-s3control/src/main/java/com/amazonaws/services/s3control/internal/handlers/EndpointHandler.java