src/vs/workbench/contrib/preferences/browser/settingsTreeModels.ts/SettingsTreeGroupElement/children
class SettingsTreeGroupElement:	set children(newChildren: SettingsTreeGroupChild[]) {
		this._children = newChildren;

		this._childSettingKeys = new Set();
		this._children.forEach(child => {
			if (child instanceof SettingsTreeSettingElement) {
				this._childSettingKeys.add(child.setting.key);
			}
		});
	}