while (session == null) {
      timeout.waitUntilNotified(this);
    }
  }

  /** Starts a real time messaging session. */
  public void startRtm() throws IOException {
    String accessToken;
    synchronized (this) {
      accessToken = session.access_token;
    }

    RtmSession rtmSession = new RtmSession(slackApi);
    rtmSession.open(accessToken);