code: public static Response post(String url, File file, String username, String password) throws URISyntaxException, HttpException {
          return postMultiPart(new HttpPost(url), new FileBody(file), new UsernamePasswordCredentials(username, password), null);
      }
docs: Performs an HTTP POST on the given URL.
  Basic auth is used if both username and password are not null
  
  @param url      The URL to connect to.
  @param file     The file to send as MultiPartFile.
  @param username username
  @param password password
  @return The HTTP response as Response object.
  @throws URISyntaxException
  @throws HttpException