code: @Nonnull
    @ReturnsMutableCopy
    public ICommonsList <IIndexerWorkItem> stop ()
    {
      // don't take any more actions
      m_aImmediateCollector.stopQueuingNewObjects ();
  
      // Get all remaining objects and save them for late reuse
      final ICommonsList <IIndexerWorkItem> aRemainingItems = m_aImmediateCollector.drainQueue ();
  
      // Shutdown the thread pool afterwards
      ExecutorServiceHelper.shutdownAndWaitUntilAllTasksAreFinished (m_aSenderThreadPool);
  
      return aRemainingItems;
    }
docs: Stop the indexer work queue immediately.
  
  @return The list of all remaining objects in the queue. Never
  <code>null</code>.