code: private HttpResponse executeUnparsed(boolean usingHead) throws IOException {
      HttpResponse response;
      if (uploader == null) {
        // normal request (not upload)
        response = buildHttpRequest(usingHead).execute();
      } else {
        // upload request
        GenericUrl httpRequestUrl = buildHttpRequestUrl();
        HttpRequest httpRequest = getAbstractGoogleClient()
            .getRequestFactory().buildRequest(requestMethod, httpRequestUrl, httpContent);
        boolean throwExceptionOnExecuteError = httpRequest.getThrowExceptionOnExecuteError();
  
        response = uploader.setInitiationHeaders(requestHeaders)
            .setDisableGZipContent(disableGZipContent).upload(httpRequestUrl);
        response.getRequest().setParser(getAbstractGoogleClient().getObjectParser());
        // process any error
        if (throwExceptionOnExecuteError && !response.isSuccessStatusCode()) {
          throw newExceptionOnError(response);
        }
      }
      // process response
      lastResponseHeaders = response.getHeaders();
      lastStatusCode = response.getStatusCode();
      lastStatusMessage = response.getStatusMessage();
      return response;
    }
docs: Sends the metadata request using the given request method to the server and returns the raw
  metadata {@link HttpResponse}.