code: @UnstableApi
      public final void executeAfterEventLoopIteration(Runnable task) {
          ObjectUtil.checkNotNull(task, "task");
          if (isShutdown()) {
              reject();
          }
  
          if (!tailTasks.offer(task)) {
              reject(task);
          }
  
          if (wakesUpForTask(task)) {
              wakeup(inEventLoop());
          }
      }
docs: Adds a task to be run once at the end of next (or current) {@code eventloop} iteration.
  
  @param task to be added.