Unhappy cities revolt to its own city state, where is it in the github?

[toxyy]

So I've searched the github for the keywords revolt, revolution, rebel, rebellion, and I've only been able to find info about city state quests and vassal liberation, but not cities revolting to its own city state. Can someone point me in the right direction to find the function(s) related to this? I want to compare it and Gedemon's Reovlutions.