Display coverage per line and general overview

Could you please point me at the extension points that would allow to display something like Git UI uses: individual blocks of lines on the left side of the editor, and similarly blocks of lines on the right side (a little to the left from the scrollbar)? If there is an existing code in the open source platform, or existing plugins, this would be even better :slight_smile:

For more context: I’d like to display coverage information.

The Git plugin is open-source.
Also, there should be Java coverage plugin implementations in intellij-community.