public void removeListener(@NotNull ConfigurationListener listener){
  if (myListeners != null) {
    myListeners.remove(listener);
    if (myListeners.isEmpty()) {
      myListeners=null;
    }
  }
}

public void removeListener ( @ NotNull ConfigurationListener listener ) { if ( myListeners != null ) { myListeners . remove ( listener ) ; if ( myListeners . isEmpty ( ) ) { myListeners = null ; } } }
removes a listener such that it is no longer notified of changes
