extensions/markdown-language-features/src/languageFeatures/diagnostics.ts/FileLinkMap/constructor
class FileLinkMap:	constructor(links: Iterable<MdLink>) {
		for (const link of links) {
			if (link.href.kind !== 'internal') {
				continue;
			}

			const existingFileEntry = this._filesToLinksMap.get(link.href.path);
			const linkData = { source: link.source, fragment: link.href.fragment };
			if (existingFileEntry) {
				existingFileEntry.outgoingLinks.push(linkData);
			} else {
				this._filesToLinksMap.set(link.href.path, { outgoingLinks: [linkData] });
			}
		}
	}