@Override
  public AccessToken refreshAccessToken() throws IOException {
    Socket socket = new Socket("localhost", this.getAuthPort());
    socket.setSoTimeout(READ_TIMEOUT_MS);
    AccessToken token;
    try {    
      PrintWriter out =
        new PrintWriter(socket.getOutputStream(), true);
      out.println(GET_AUTH_TOKEN_REQUEST);
    
      BufferedReader input =
          new BufferedReader(new InputStreamReader(socket.getInputStream()));
      input.readLine(); // Skip over the first line
      JsonParser parser = OAuth2Utils.JSON_FACTORY.createJsonParser(input);
      List<Object> messageArray = (List<Object>) parser.parseArray(ArrayList.class, Object.class);
      String accessToken = messageArray.get(ACCESS_TOKEN_INDEX).toString();
      token =  new AccessToken(accessToken, null);
    } finally {
      socket.close();
    }
    return token;
  }