code: public final HttpResponse executeUnparsed() throws IOException {
      // must set clientAuthentication as last execute interceptor in case it needs to sign request
      HttpRequestFactory requestFactory =
          transport.createRequestFactory(new HttpRequestInitializer() {
  
            public void initialize(HttpRequest request) throws IOException {
              if (requestInitializer != null) {
                requestInitializer.initialize(request);
              }
              final HttpExecuteInterceptor interceptor = request.getInterceptor();
              request.setInterceptor(new HttpExecuteInterceptor() {
                public void intercept(HttpRequest request) throws IOException {
                  if (interceptor != null) {
                    interceptor.intercept(request);
                  }
                  if (clientAuthentication != null) {
                    clientAuthentication.intercept(request);
                  }
                }
              });
            }
          });
      // make request
      HttpRequest request =
          requestFactory.buildPostRequest(tokenServerUrl, new UrlEncodedContent(this));
      request.setParser(new JsonObjectParser(jsonFactory));
      request.setThrowExceptionOnExecuteError(false);
      HttpResponse response = request.execute();
      if (response.isSuccessStatusCode()) {
        return response;
      }
      throw TokenResponseException.from(jsonFactory, response);
    }
docs: Executes request for an access token, and returns the HTTP response.
  
  <p>
  To execute and parse the response to {@link TokenResponse}, instead use {@link #execute()}.
  </p>
  
  <p>
  Callers should call {@link HttpResponse#disconnect} when the returned HTTP response object is
  no longer needed. However, {@link HttpResponse#disconnect} does not have to be called if the
  response stream is properly closed. Example usage:
  </p>
  
  <pre>
  HttpResponse response = tokenRequest.executeUnparsed();
  try {
  process the HTTP response object
  } finally {
  response.disconnect();
  }
  </pre>
  
  @return successful access token response, which can then be parsed directly using
  {@link HttpResponse#parseAs(Class)} or some other parsing method
  @throws TokenResponseException for an error response