@Override
 public String getAccessTokenSecret() {
   if (accessToken == null) {
     return null;
   }
   return accessToken.getSecret();
 }
 @Override
 public String getAccessTokenValue() {
   if (accessToken == null) {
     return null;
   }
   return accessToken.getToken();
 }
  @Override
  public String getAuthorizationURL() throws IOException {
    String rtu = getOAuthRequestTokenURL();
    if (rtu == null) {
      return getOAuthAuthorizationURL();
    }

    try {
      requestToken = auth.requestTemporaryCredentials(new URL(rtu), Method.GET);
    } catch (MalformedURLException e) {
      // should never happen
      throw new RuntimeException(e);
    }
    return getOAuthAuthorizationURL() + requestToken.getToken();
  }