cant upload files

```
// openai
// To use dotenv, you need to add the "io.github.cdimascio:dotenv-kotlin:version"
// dependency. Then you can add a .env file in your project directory.
//String key = Dotenv.load().get("OPENAI_TOKEN");
openai = OpenAI.builder()
.apiKey("API_KEY")
.build();

messages = new ArrayList<>();
messages.add(ChatMessage.toSystemMessage("Help the user with their problem."));

// Here you can change the model's settings, add tools, and more.
request = ChatRequest.builder()
.model("gpt-4o")
.messages(messages)
.build();
```
```
private byte[] downloadFile(String url) throws ClientProtocolException, IOException {
HttpGet request = new HttpGet(url.replace(" ", "%20"));
request.addHeader("sec-ch-ua",
"\" Not A;Brand\";v=\"99\", \"Chromium\";v=\"130\", \"Microsoft Edge\";v=\"130\"");
request.addHeader("X-Requested-With", "XMLHttpRequest");
request.addHeader("sec-ch-ua-mobile", "?0");
request.addHeader(
"User-Agent",
"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Safari/537.36 Edg/130.0.0.0");
request.addHeader("sec-ch-ua-platform", "\"Windows\"");
request.addHeader("Origin", url); // to be fixed
request.addHeader("Sec-Fetch-Site", "same-origin");
request.addHeader("Sec-Fetch-Mode", "cors");
request.addHeader("Sec-Fetch-Dest", "empty");
request.addHeader("Referer", url);
request.addHeader("Accept-Language", "en-US,en;q=0.9");
request.addHeader("sec-gpc", "1");
DefaultHttpClient httpClient = new DefaultHttpClient();
request.addHeader(
"sec-ch-ua",
"\" Not A;Brand\";v=\"99\", \"Chromium\";v=\"100\", \"Microsoft Edge\";v=\"100\"");
request.addHeader("sec-ch-ua-mobile", "?0");
request.addHeader(
"User-Agent",
"Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4863.0 Safari/537.36 Edg/100.0.1163.1");
CloseableHttpResponse response = httpClient.execute(request);
InputStream is = response.getEntity().getContent();
byte[] b = new byte[1024];
int r;
ByteArrayOutputStream baos = new ByteArrayOutputStream();
while ((r = is.read(b)) != -1) {
baos.write(Arrays.copyOf(b, r));
baos.flush();
}
baos.close();
return baos.toByteArray();
}
```
```
if (label.equalsIgnoreCase("chatgpt")) {
if (args.length == 0) {
sender.sendMessage('\r' + "Unknown translation key: command.unknown.argument");
sender.sendMessage('\r' + label + " " + String.join(" ", args)
+ "Unknown translation key: command.context.here");
return;
} else if (args[0].equalsIgnoreCase("upload") && args.length >= 2) {
String url = args[1];
String fn = url.substring(url.lastIndexOf("/") + 1, url.length());
System.out.println(fn);
byte[] b = null;
try {
b = downloadFile(url);
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
UploadFileRequest ufr = UploadFileRequest.builder().byteArray(fn, b).purpose(FilePurpose.ASSISTANTS).build();
FileObject fo = openai.files().upload(ufr);
System.out.println(fo);
return;
}
String input = String.join(" ", args);
messages.add(ChatMessage.toUserMessage(input));
ChatResponse response = openai.createChatCompletion(request);
sender.sendMessage('\r' + response.get(0).getMessage().getContent());
messages.add(response.get(0).getMessage());
}
```
when running command `chatgpt upload https://litter.catbox.moe/f4a2f1.jpg` it results in this error
```
java.io.IOException: Unexpected code Response{protocol=http/1.1, code=415, message=Unsupported Media Type, url=https://api.openai.com/v1/files}, received: {
"error": {
"message": "Invalid Content-Type header (application/json; charset=utf-8), expected multipart/form-data. (HINT: If you're using curl, you can pass -H 'Content-Type: multipart/form-data')",
"type": "invalid_request_error",
"param": null,
"code": null
}
}

at com.cjcrafter.openai.RequestHelper.executeRequest(RequestHelper.kt:66)
at com.cjcrafter.openai.RequestHelper.executeRequest(RequestHelper.kt:77)
at com.cjcrafter.openai.files.FileHandlerImpl.upload(FileHandlerImpl.kt:11)
```
and yes im fully aware im not doing my code right if i intend on actually using the uploaded file in the given chat thread to talk to gpt-4o, this is just a mere test of the file upload api for ChatGPT-Java-API which seems to be failing
`Invalid Content-Type header (application/json; charset=utf-8), expected multipart/form-data. (HINT: If you're using curl, you can pass -H 'Content-Type: multipart/form-data')` seems to be a error in ChatGPT-Java-API and not my code

Start with FileHandlerImpl.kt and RequestHelper.kt, using the reported upload call and 415 response as the reproduction. Trace how the file upload request is built and verify its content type against the OpenAI files endpoint. Done means the upload request is accepted instead of being sent as application/json.

Written by the indexing model from the issue text.