Guidelines for backporting

[Stephen Colebourne]

Is there a page that discusses what should/can be backported (as
opposed to how, which does seem to be documented).

In particular, I have questions around:
- what is the goal of update releases beyond security patches?
- what is intended? bug fixes vs performance fixes vs optimisations vs features
- can the Javadoc can be changed or not?
- what does "no spec changes" really mean?

I'm hoping such a page exists already, but I can't find it if it does.

Stephen