return waitFor(closingFunction5, ClosingFunction5.class);
    }

    <T> T waitFor(T delegate, Class<T> type) {
      checkState(proxy == null);
      T proxyObject =
          Reflection.newProxy(
              type,
              new InvocationHandler() {
                @Override
                public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {