src/vs/workbench/contrib/files/common/explorerModel.ts/ExplorerItem/fileNester
class ExplorerItem:	private get fileNester(): ExplorerFileNestingTrie {
		if (!this.root._fileNester) {
			const nestingConfig = this.configService.getValue<IFilesConfiguration>({ resource: this.root.resource }).explorer.fileNesting;
			const patterns = Object.entries(nestingConfig.patterns)
				.filter(entry =>
					typeof (entry[0]) === 'string' && typeof (entry[1]) === 'string' && entry[0] && entry[1])
				.map(([parentPattern, childrenPatterns]) =>
					[
						this.getPlatformAwareName(parentPattern.trim()),
						childrenPatterns.split(',').map(p => this.getPlatformAwareName(p.trim().replace(/\u200b/g, '')))
					] as [string, string[]]);

			this.root._fileNester = new ExplorerFileNestingTrie(patterns);
		}
		return this.root._fileNester;
	}