We have an on premise S3 service which I try to connect using the Java AWS SDK v2.
My application uses Spring-boot 3 and my maven build file contains dependency:

    <dependency>
        <groupId>software.amazon.awssdk</groupId>
        <artifactId>s3</artifactId>
        <version>2.24.6</version>
    </dependency>       

The configuration of the S3 client looks like:

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.s3.S3Client;

@Configuration
public class FileStore2Configuration {

    @Bean
    S3Client s3Client(String host, String accessKey, String credentials) {
        System.setProperty("aws.accessKeyId", accessKey);
        System.setProperty("aws.secretAccessKey", credentials);
        System.setProperty("aws.region", Region.EU_WEST_1.id());
        System.setProperty("aws.endpointUrl", host);
        S3Client client= S3Client.builder()
            .endpointOverride(URI.create(host))
            .forcePathStyle(Boolean.TRUE)
            .build();
        return client;
    }
 }

This client is injected in a Component to build a presigned url:

import software.amazon.awssdk.services.s3.S3Client;
import software.amazon.awssdk.services.s3.presigner.S3Presigner;
import software.amazon.awssdk.services.s3.presigner.model.PresignedPutObjectRequest;
import software.amazon.awssdk.services.s3.presigner.model.PutObjectPresignRequest;

@Component
public class AWS2FileStoreService implements FileStoreService {

    public static final Logger LOGGER = LoggerFactory.getLogger(AWS2FileStoreService.class);

    private S3Client s3Client;
    
    public String bucket;

    public AWS2FileStoreService(S3Client awsClient, String bucket) {
        LOGGER.info("AWSFileStoreService initialized for bucket {}",bucket);
        this.bucket=bucket;
        this.s3Client = awsClient;
    }

    @Override
    public String createUploadLink(String path, String filename) throws Exception {
        String fullName = concat(path,filename);
        try (S3Presigner presigner = S3Presigner.builder().s3Client(s3Client).build()) {
            PutObjectRequest objectRequest = PutObjectRequest.builder()
                    .bucket(bucket)
                    .key(fullName)
                    .build();

            PutObjectPresignRequest presignRequest = PutObjectPresignRequest.builder()
                    .signatureDuration(Duration.ofDays(1))  // The URL will expire in 1 day.
                    .putObjectRequest(objectRequest)
                    .build();

            PresignedPutObjectRequest presignedRequest = presigner.presignPutObject(presignRequest);
            LOGGER.info("Presigned URL: [{}]", presignedRequest.url());
            LOGGER.info("HTTP method: [{}]", presignedRequest.httpRequest().method());
            if(!presignedRequest.isBrowserExecutable())
                LOGGER.warn("Presigned url [{}] is not browser executable",presignedRequest.url());

            return presignedRequest.url().toExternalForm();
        }
    }
}

When I try this implementation:

public class AmazonS3SmokeTry {
    private static String host="https://my.internal.server:9021";
    private static String accessKey="internalUser";
    private static String credentials="internalPW";

    public static void main(String[] args) throws Exception {
        S3Client client=new FileStore2Configuration().s3Client(host, accessKey, credentials);
        AWS2FileStoreService filestore=new AWS2FileStoreService(client,"bucket-dev"); 
        System.out.println("upload link to taskupload/newfile.xml:"+filestore.createUploadLink("/taskupload", "newfile.xml"));
    }
}

the output is:

upload link to taskupload/newfile.xml:https://bucket-dev.s3.eu-west-1.amazonaws.com//taskupload/newfile.xml?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20240613T112924Z&X-Amz-SignedHeaders=host&X-Amz-Credential=internal-user%2F20240613%2Feu-west-1%2Fs3%2Faws4_request

Notice it ignores my host configuration and the bucket name is used as part of the domain where it should be part of the path (hence call on .forcePathStyle(Boolean.TRUE).
I would expect a URL like : https://my.internal.server:9021/bucket-dev/taskupload/newfile.xml?…

As you can see I tried setting the system property aws.endpointUrl and setting the host through the S3Client builder .endpointOverride(host) method. However all without success.

Any suggestions how I can make this work ?
Thanks already.