code: private HttpEntity buildBodyWithFile(File file) {
          MultipartEntityBuilder builder = MultipartEntityBuilder.create();
          builder.addBinaryBody("file", file,
                  ContentType.APPLICATION_OCTET_STREAM, file.getName());
          HttpEntity multipart = builder.build();
          return multipart;
      }
docs: Builds request body with a given file
  @param file file containing binary data.