src/vs/platform/contextkey/browser/contextKeyService.ts/stringifyURIs
function stringifyURIs(contextValue: any): any {
	return cloneAndChange(contextValue, (obj) => {
		if (typeof obj === 'object' && (<MarshalledObject>obj).$mid === MarshalledId.Uri) {
			return URI.revive(obj).toString();
		}
		if (obj instanceof URI) {
			return obj.toString();
		}
		return undefined;
	});
}