src/vs/workbench/contrib/search/common/searchModel.ts/FolderMatch/getDownstreamFileMatch
class FolderMatch:	getDownstreamFileMatch(uri: URI): FileMatch | null {
		const directChildFileMatch = this._fileMatches.get(uri);
		if (directChildFileMatch) {
			return directChildFileMatch;
		}

		const folderMatch = this.getFolderMatch(uri);
		const match = folderMatch?.getDownstreamFileMatch(uri);
		if (match) {
			return match;
		}

		return null;
	}