Minor code cleanup

I was inspecting the codebase to figure out something when I saw a few IntelliJ suggestions. Eventually, I ran the inspection tool and went through the enormous list of possible issues. I think these are changes for the better. Please let me know, if you do not agree with some of the types of changes, I can modify the PR to make everyone happy.
Well I just followed IntelliJ's hint saying it's not possible already to override a private field which sort of makes sense. Basically it's saying that final is redundant.Maybe the author was trying to signal that it should be not be overridden even if it one day becomes protected or private. Another explanation could be some bizarre optimization rule I am unaware of.