Spring Reactive call router handler method from another router handler method

Question

I have written a router function that as two API calls -

1. Upload to s3
2. download from s3

My Router function is as below -

 @Bean
public RouterFunction<ServerResponse> s3ApiRouter() {
    return route(POST("/s3/upload").and(accept(MediaType.APPLICATION_JSON)), s3RouterHandler::handleUpload)
            .andRoute(GET("/s3/download/{name}"), s3RouterHandler::downloadFromS3);
}

My objective here is to upload a file to S3 and download the file, process it, and reupload.

So, in the "/s3/download/{name}" (download API call) - I download the image, process it and I have to call the "/s3/upload" method to reupload the file.

I'm able to call the "/s3/upload" independently,

I'm not able to call "/s3/upload**" from the "/s3/download/{name}" method.**

my code for the - "/s3/upload"

  Mono<ServerResponse> handleUpload(ServerRequest serverRequest) {
    Mono<ServerResponse> response = uploadResource.filepartUploadHandler(serverRequest);
    return response;
}

2. "/s3/download/{name}"

   Mono downloadFromS3(ServerRequest serverRequest) {

    log.info("handle request {} - {}", serverRequest.method(), serverRequest.path());
    String name = serverRequest.pathVariable("name");
    InputStreamResource inputStreamResource = null;
    File outBoundFile = null;
    try {
        InputStream is = uploadResource.downloadFileFromS3Bucket(name);
        if (!isNull(is)) {
            File file = File.createTempFile(FilenameUtils.removeExtension(name),
                    "." + FilenameUtils.getExtension(name)); // vitrual File
            FileUtils.copyInputStreamToFile(is, file);
            String urlFilePath = (String) rotationUtil.rotate(file, serverRequest);
            inputStreamResource = new InputStreamResource(is);
            if (!isNull(urlFilePath))
                outBoundFile = new File(urlFilePath);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
    return ServerResponse.created(URI.create("/s3/upload"))
            .bodyValue(BodyInserters.fromMultipartData(fromFile(outBoundFile)));
   

   }

   public MultiValueMap<String, HttpEntity<?>> fromFile(File file) {

    MultipartBodyBuilder builder = new MultipartBodyBuilder();
    builder.part("files", new FileSystemResource(file));
    return builder.build();
   

   }

How do I call handleUpload method from the downloadFromS3 ?.