*
   * However, for a variety of reasons, Google developers have written a ton of code over the past
   * decade that assumes that they can use checkNotNull for non-precondition checks. I had hoped to
   * take a principled stand on this, but the amount of such code is simply overwhelming. To avoid
   * creating a lot of compile errors that users would not find to be informative, we're giving in

      ATOMIC_HELPER.putNext(this, next);
    }

    void unpark() {
      // This is racy with removeWaiter. The consequence of the race is that we may spuriously call
      // unpark even though the thread has already removed itself from the list. But even if we did
      // use a CAS, that race would still exist (it would just be ever so slightly smaller).
      Thread w = thread;
      if (w != null) {
        thread = null;