This is interesting discussion.
I want to point out that abantecart was not based on opencart and was not forked. Idea was to make it similar in construct to help developers that support abantecart and opnecart to navigate them both easily. I hope everybody understand this point and agree.
I agree that it should be mentioned, if something from open cart got accidentally inserted into abantecart.
We review the code, but since we had some old developers on the team in the beginning, it is possible that something got copied and was not noticed.
First we need to identify what exactly was the code and give a credit. If you help pointing out the areas I will check.