Java Proxy POST request to secondary server

Here is the code I have so far.

What does works is reading all form name/values from the original request. What does not work is the new server does not receive any of the newly assigned form name/values. Basically they dont seem to get transmitted to the secondary server.

There might be an easier way to do so?? All I need is to trigger on a specific form field from the new server and redirect to a sub-server that will handle the request and pass back the results thru the main server to the client (proxying).

String value = String.format("https://%s.myotherserver.com%s", "sub1", request.getRequestURI());

HttpPost uploadFile = new HttpPost(value);
uploadFile.addHeader("Content-Type", request.getContentType());
MultipartEntityBuilder builder = MultipartEntityBuilder.create();
builder.setMode(HttpMultipartMode.BROWSER_COMPATIBLE);

ContentBody cbFile = new InputStreamBody(request.getPart("audio").getInputStream(), ContentType.create("audio/webm"),"audio.ogg");
builder.addPart("audio", cbFile);

builder.addPart("text", new StringBody(request.getParameter("text"),ContentType.DEFAULT_TEXT));
builder.addPart("email", new StringBody(request.getParameter("email"),ContentType.DEFAULT_TEXT));

// now add the other original form name/values to new request
do
{
    String parameterName = reqParameterNames.nextElement().toString();
    Object parameterValue = request.getParameter(parameterName);
    if (!privateParameters.contains("p_"+parameterName)) {
        builder.addPart(new FormBodyPart(parameterName, new StringBody((String) parameterValue,ContentType.DEFAULT_TEXT)));
    }
} while (reqParameterNames.hasMoreElements());

HttpEntity multipart = builder.build();
uploadFile.setEntity(multipart);

CloseableHttpClient httpClient2 = HttpClients.createDefault();
CloseableHttpResponse statusCode = httpClient2.execute(uploadFile);
HttpEntity responseEntity = statusCode.getEntity();
StringBuffer responseBuffer = new StringBuffer();
OutputStream output = response.getOutputStream();
ByteStreams.copy(responseEntity.getContent(), output);
output.flush();

Solution

I finally managed to get it to work with the following code. I hope this can help someone else;

MultipartEntityBuilder mb = null; 
org.apache.http.HttpEntity entity =null;
String value = String.format("https://%s.myotherserver.com%s", "sub1", request.getRequestURI());

mb = MultipartEntityBuilder.create();
mb.addTextBody("noproxy", "true");
mb.addTextBody("text", request.getParameter("text"));
mb.addTextBody("email", request.getParameter("email"));
mb.addBinaryBody("audio", new File(inputAudioFilename));

entity = mb.build();
URLConnection conn = new URL(urlStr[i]).openConnection();
conn.setDoOutput(true);
conn.addRequestProperty(entity.getContentType().getName(), entity.getContentType().getValue());
conn.addRequestProperty("Content-Length", String.valueOf(entity.getContentLength()));
OutputStream fout = conn.getOutputStream();
entity.writeTo(fout);//write multi part data...
fout.flush();
fout.close();
OutputStream output = response.getOutputStream();
output.flush();
                    ByteStreams.copy(conn.getInputStream(),response.getOutputStream());

conn.getInputStream().close();