docs: private boolean registerListener(String newPath, ArtifactListenerSelector newListener) {
          boolean updatedCoveringPaths = addCoveringPath(newPath);
  
          Collection<ArtifactListenerSelector> listenersForPath = listeners.get(newPath);
          if ( listenersForPath == null ) {
              // Each listeners collection is expected to be small.
              listenersForPath = new LinkedList<ArtifactListenerSelector>();
              listeners.put(newPath, listenersForPath);
          }
          listenersForPath.add(newListener);
  
          return ( updatedCoveringPaths );
      }