Recently I was talking to a friend and the topic of credit cards came up. I asked my friend (xx) if they had a credit card:

> ところで、xxはクレジットカードを持ってる？

and got the following response:

> そりゃあ持っているでしょう**に**。

I'm not too sure what the に at the end means, but searching around the internet it seems to be related to のに. However, sentences that end with のに typically indicate disappointment/regret etc and I don't believe that was the case here. I found [this][1]:

> 
あなた、それくらい分かっているでしょうに。
You know that, don't you?
この場合の、don't you? に相当するのが、「でしょうに」です。


which seems close in meaning, but it doesn't feel like it's from のに. Any elucidation on this would be helpful.

  [1]: https://hinative.com/ja/questions/60469