src/vs/platform/markers/common/markerService.ts/DoubleResourceMap/values
class DoubleResourceMap:	values(key?: URI | string): Iterable<V> {
		if (typeof key === 'string') {
			return this._byOwner.get(key)?.values() ?? Iterable.empty();
		}
		if (URI.isUri(key)) {
			return this._byResource.get(key)?.values() ?? Iterable.empty();
		}

		return Iterable.map(Iterable.concat(...this._byOwner.values()), map => map[1]);
	}