public SequentialListenerManager updateExecutor(Listener listener,ListenerExecutor executor){
  if (!listenerExists(listener))   throw new RuntimeException("Listener " + listener + " does not exist in this manager");
  int index=listeners.indexOf(listener);
  listenerExecutors.set(index,executor);
  return this;
}

public SequentialListenerManager updateExecutor ( Listener listener , ListenerExecutor executor ) { if ( ! listenerExists ( listener ) ) throw new RuntimeException ( "Listener " + listener + " does not exist in this manager" ) ; int index = listeners . indexOf ( listener ) ; listenerExecutors . set ( index , executor ) ; return this ; }
replace the executor for the supplied listener
