These are not documented because there generally is no reason to touch them - settings other than the defaults have also not been widely tested.
Still, what if I wanted to change a JVM parameter at all, at my own risk?
Where shall I look?
As I said – undocumented
If you really have the motivation, you can discover this on your own by using file searching tools to look for common JVM options that folks set inside our file folders…
Don’t mean to be obtuse, but can’t really point you to stuff I just said “don’t touch”.