Passing parameters in integration test JAVA

I try to pass parameters in post request in integration test, but I get response that required parameter "source" aint detected. Maybe you will know what is cause. Thank you.

public void testUploadBundleFromRepository() throws IOException, InterruptedException {

    String boundary = "---------------"+ UUID.randomUUID().toString();

    String uri = String.format("http://%s:%d/upload/", HOST, PORT);

    HttpPost httpPost = new HttpPost(uri);
    httpPost.setHeader(HTTP.CONTENT_TYPE, ContentType.MULTIPART_FORM_DATA.getMimeType()+";boundary="+boundary);

    List<NameValuePair> postParameters = new ArrayList<>();
    postParameters.add(new BasicNameValuePair("source","repo"));
    postParameters.add(new BasicNameValuePair("id","1"));
    postParameters.add(new BasicNameValuePair("start", "true"));
    httpPost.setEntity(new UrlEncodedFormEntity(postParameters, "UTF-8"));

    HttpResponse response = getHttpClient().execute(httpPost);

    //assert in future
}