How does the "Auto Generate" function in Lighting settings work?

Auto Generate rebuilds the lighting data as you edit the scene.
The tutorial page says

Examples include setting an object as static, adjusting a light, etc. How does detecting only lighting-related changes in the scene work? Can I find the functions to do that anywhere in the Editor, or Lightmapper, or is it a per game object flag?

The purpose is to hook into this behavior of detecting changes that would require rebuilding the lighting data in order to write a custom "auto light generation" script for use with third party lightmappers.