private void addSessionsRegistrationListener(final ThirdPartyRegistrationListener listener){
synchronized (this) {
    if ((null != listener) && (mThirdPartyRegistrationListeners.indexOf(listener) == -1)) {
      mThirdPartyRegistrationListeners.add(listener);
    }
  }
}

private void addSessionsRegistrationListener ( final ThirdPartyRegistrationListener listener ) { synchronized ( this ) { if ( ( null != listener ) && ( mThirdPartyRegistrationListeners . indexOf ( listener ) == - 1 ) ) { mThirdPartyRegistrationListeners . add ( listener ) ; } } }
add a listener to the third party server .
