Unfortunately this isn't really possible to remove these classes. They have additional changes over and above the jdk8 classes. We could move it into a different package though if we wanted to.
To be honest the only reason this is still really needed is for the BoundedConcurrentHashMapV8. I have been talking with Dan on and off for a while about even possibly looking into using a different map implementation (such as caffeine or something else equivalent). We haven't looked into it very seriously though.
We could look into this more if people think we want to tackle that.
- Will