runnables = null; // allow GC to free listeners even if this stays around for a while.
      }
      while (list != null) {
        executeListener(list.runnable, list.executor);
        list = list.next;
      }
    }

    private static void executeListener(Runnable runnable, Executor executor) {
      try {
        executor.execute(runnable);
      } catch (RuntimeException e) {
        log.log(