To be fair the API given is pretty c*p when you have to target older Androids as well (and don't want to give them an uglier icon). If I remember right I had to simplify the icon as well (remove transparency I think) because Android doesn't like many things that are okay in svgs.
I just used Android Studio to generate the icon for older versions. Yes, I would assume no transparency, since it needs to be a simple single-layered image, AFAIK.
