JS将包含多个文件的formData发送到java API

我是JAVA新手，我正在尝试创建一个JAVA api，从JS前端接收文件数组。但我得到“415不支持的媒体类型错误”。我不确定我可以使用什么样的类或库来实现这一点。下面是我的JavaAPI代码

@POST
@Timed
@Path("/prepare_file_segments")
@Produces({"application/json"})
@Consumes(MediaType.MULTIPART_FORM_DATA)
public ArrayList<ArrayList<String>> prepareFileSegments(
        @FormDataParam("files") FormDataMultiPart bodyParts,
        @Context HttpServletRequest request
) {
ArrayList<ArrayList<String>> headers = new ArrayList<>();
    for (BodyPart part : bodyParts.getBodyParts()) {
        try {
            InputStream inputStream = part.getEntityAs(InputStream.class);
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
            String[] headerRow = bufferedReader.readLine().split("\t");
            List<String> list = Arrays.asList(headerRow);
            ArrayList header = new ArrayList(list);
            headers.add(header);
        } catch (FileNotFoundException e){
            log.error("prepareFileSegments failed " + e.getMessage());
            throw new FileNotFoundException(e.getMessage());
        } catch (IOException e) {
            log.error("prepareFileSegments failed " + e.getMessage());
            throw new IOException(e.getMessage());
        }
    }
    return headers;
}

我现在无法使用调试器。这有点妨碍我。但我这样做对吗？这个api应该使用什么类和库？有人能给我举个例子吗？多谢各位

let formData = new FormData();
formData.append('files', FILES)
wretch('url')
.json(formData)
.post()
.json()