I was in a research group for my MSc. dissertation (computational work) during which I developed quite a bit of code that went on being used in a publication which I co-authored (no code was published at the time - I know how much of a bad practice this is, it was not dependent on me).
Now, without changing much of the code (I would say the bulk of the code remains unchanged), my advisor wants to make it publicly accessible as part of a new publication. My advisor does not want me to be one of the authors, claiming that I do not own the code and that the code is now owned by my advisor and by the institute where she works and where I did my MSc. dissertation work. The changes were done by people who are now members of this group.
For the sake of not going through too much trouble, I would be happy foregoing this whole situation, but as a matter of principle this really bothers me. I do not feel like I am in a position where this can hurt or affect me, but I fear it may happen to other people, too. What would be the usual thing to do? Is being confrontational about this worth it? Who actually owns the code in this situation and what would be the right thing to do?