}

    @SuppressWarnings("unchecked") // proxy for a generic class
    <V1, V2, V3, V4, V5, U> ClosingFunction5<V1, V2, V3, V4, V5, U> waitFor(
        ClosingFunction5<V1, V2, V3, V4, V5, U> closingFunction5) {
      return waitFor(closingFunction5, ClosingFunction5.class);
    }

    <T> T waitFor(T delegate, Class<T> type) {
      checkState(proxy == null);
      T proxyObject =