code: public void addOneShotAfterTask(final long fireAfter, final TimeUnit timeUnit, final Runnable task) {
  
          fireOnceAfterTasks.add(new FireOnceTask(task, timeUnit, fireAfter));
      }
docs: Add a task that gets executed once.
  
  @param fireAfter run task after time period
  @param timeUnit  unit for fireAfter
  @param task      task to perform