code: public static void unwatch(Thread thread, Runnable task) {
          if (thread == null) {
              throw new NullPointerException("thread");
          }
          if (task == null) {
              throw new NullPointerException("task");
          }
  
          schedule(thread, task, false);
      }
docs: Cancels the task scheduled via {@link #watch(Thread, Runnable)}.