src/vs/workbench/services/search/common/searchService.ts/SearchService/getSchemesInQuery
class SearchService:	private getSchemesInQuery(query: ISearchQuery): Set<string> {
		const schemes = new Set<string>();
		if (query.folderQueries) {
			query.folderQueries.forEach(fq => schemes.add(fq.folder.scheme));
		}

		if (query.extraFileResources) {
			query.extraFileResources.forEach(extraFile => schemes.add(extraFile.scheme));
		}

		return schemes;
	}