Monitor monitor1 = new Monitor();
    Monitor monitor2 = new Monitor();
    FlagGuard guard = new FlagGuard(monitor2);
    assertThrows(IllegalMonitorStateException.class, () -> monitor1.hasWaiters(guard));
  }

  public void testNullMonitorInGuardConstructorThrowsNPE() {
    assertThrows(NullPointerException.class, () -> new FlagGuard(null));
  }

  public void testIsFair() {

    Monitor monitor1 = new Monitor();
    Monitor monitor2 = new Monitor();
    FlagGuard guard = new FlagGuard(monitor2);
    assertThrows(IllegalMonitorStateException.class, () -> monitor1.hasWaiters(guard));
  }

  public void testNullMonitorInGuardConstructorThrowsNPE() {
    assertThrows(NullPointerException.class, () -> new FlagGuard(null));
  }

  public void testIsFair() {

   * and leaves, calling signalNextWaiter. With traditional locks and conditions, all the conditions
   * need to be signalled because it is not known which if any of them have waiters (and hasWaiters
   * can't be used reliably because of a check-then-act race). With our Monitor guards, we only
   * signal the first active guard that is satisfied. But the corresponding thread may have already

   */
  private boolean casWaiters(@Nullable Waiter expect, @Nullable Waiter update) {
    return ATOMIC_HELPER.casWaiters(this, expect, update);
  }

  /**
   * Performs a {@linkplain java.lang.invoke.VarHandle#getAndSet get-and-set} operation on {@link
   * #waitersField}.
   */
  private final @Nullable Waiter gasWaiters(Waiter update) {
    return ATOMIC_HELPER.gasWaiters(this, update);
  }

  /**

   */
  private boolean casWaiters(@Nullable Waiter expect, @Nullable Waiter update) {
    return ATOMIC_HELPER.casWaiters(this, expect, update);
  }

  /**
   * Performs a {@linkplain java.lang.invoke.VarHandle#getAndSet get-and-set} operation on {@link
   * #waitersField}.
   */
  private final @Nullable Waiter gasWaiters(Waiter update) {
    return ATOMIC_HELPER.gasWaiters(this, update);
  }

  /**