}
    }

    @Override
    void putThread(Waiter waiter, Thread newValue) {
      UNSAFE.putObject(waiter, WAITER_THREAD_OFFSET, newValue);
    }

    @Override
    void putNext(Waiter waiter, @CheckForNull Waiter newValue) {
      UNSAFE.putObject(waiter, WAITER_NEXT_OFFSET, newValue);
    }

    /** Performs a CAS operation on the {@link #waiters} field. */
    @Override

  }

  @CanIgnoreReturnValue
  @Override
  public boolean replace(K key, @CheckForNull V oldValue, V newValue) {
    checkNotNull(key);
    checkNotNull(newValue);
    if (oldValue == null) {
      return false;
    }
    int hash = hash(key);
    return segmentFor(hash).replace(key, hash, oldValue, newValue);
  }

  @CheckForNull
  @CanIgnoreReturnValue
  @Override