volatile boolean finalizeReferentCalled;

    MockReference(FinalizableReferenceQueue frq) {
      super(new Object(), frq);
    }

    @Override
    public void finalizeReferent() {
      finalizeReferentCalled = true;
    }
  }

  /**
   * Keeps a weak reference to the underlying reference queue. When this reference is cleared, we

    public MyFinalizableWeakReference(Object x, FinalizableReferenceQueue queue) {
      super(x, queue);
    }

    @Override
    public void finalizeReferent() {}
  }

  private static class PermissivePolicy extends Policy {
    @Override
    public boolean implies(ProtectionDomain pd, Permission perm) {
      return true;
    }
  }