Retrieving headers from bodyless response

[nginocchio96]

Hello, I do apologize if there is a more appropriate place for this "issue", but the discussion page gives a 404.

I have been trying to get the response headers from a empty body response specifically the copy drive item endpoint: POST /drives/{driveId}/items/{itemId}/copy.
This code I have in which I attempt to retrieve response headers:

  final CopyPostRequestBody copyPostRequestBody = new CopyPostRequestBody();
  copyPostRequestBody.setParentReference(existingFile.getParentReference());
  copyPostRequestBody.setName("foo bar" + "." + FilenameUtils.getExtension(existingFile.getName()));
  // copy file from drive /drives/{driveId}/items/{itemId}/copy
  final HashMap<String, Object> pathParams = new HashMap<>();
  pathParams.put("baseUrl", graphServiceClient.getRequestAdapter().getBaseUrl());
  pathParams.put("driveId", existingFile.getParentReference().getDriveId());
  pathParams.put("itemId", existingFile.getId());

  RequestInformation requestInformation = new RequestInformation();
  requestInformation.httpMethod = HttpMethod.POST;
  requestInformation.urlTemplate = "{+baseUrl}/drives/{driveId}/items/{itemId}/copy";
  requestInformation.pathParameters = pathParams;
  requestInformation.setContentFromParsable(graphServiceClient.getRequestAdapter(), "application/json", copyPostRequestBody);

  HashMap<String, ParsableFactory<? extends Parsable>> errorMapping = new HashMap<>();

  // I don't think this will ever work
  final Response response = graphServiceClient.getRequestAdapter().sendPrimitive(requestInformation, errorMapping, Response.class);

I know "sendPrimitive" is incorrect, because it will try to parse the body which is null. My question is how do I correctly get the headers from this response. I think it revolves around setting a responseHandler on the requestInformation. How to actually do that is unclear to me.

Any help would be appreciated, thank you.

[nginocchio96]

I managed to find the answer on my own.

final CopyPostRequestBody copyPostRequestBody = new CopyPostRequestBody();
copyPostRequestBody.setParentReference(existingFile.getParentReference());
copyPostRequestBody.setName("foo bar" + "." + FilenameUtils.getExtension(existingFile.getName()));

final RequestInformation requestInformation = graphServiceClient
        .drives()
        .byDriveId(existingFile.getParentReference().getDriveId())
        .items()
        .byDriveItemId(existingFile.getId())
        .copy()
        .toPostRequestInformation(copyPostRequestBody);

final Request req = graphServiceClient.getRequestAdapter().convertToNativeRequest(requestInformation);
OkHttpClient okHttpClient = new OkHttpClient();
final Response response = okHttpClient.newCall(req).execute();

I just generated the RequestInformation using the graph client and sent the native request using an HTTP client. The response object has everything I need.