src/vs/workbench/services/preferences/common/preferencesModels.ts/AbstractSettingsModel/collectMetadata
class AbstractSettingsModel:	protected collectMetadata(groups: ISearchResultGroup[]): IStringDictionary<IFilterMetadata> {
		const metadata = Object.create(null);
		let hasMetadata = false;
		groups.forEach(g => {
			if (g.result.metadata) {
				metadata[g.id] = g.result.metadata;
				hasMetadata = true;
			}
		});

		return hasMetadata ? metadata : null;
	}