private boolean isFipsInvolved(String signingRegion, String arnRegion, Request<?> request) {
        if (isFipsEnabledInClientConfig(request)) {
            return true;
        }
        return isFipsRegion(signingRegion) || isFipsRegion(arnRegion);
    }
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