extensions/markdown-language-features/src/client/workspace.ts/VsCodeMdWorkspace/constructor
class VsCodeMdWorkspace:	constructor() {
		super();

		this._watcher = this._register(vscode.workspace.createFileSystemWatcher('**/*.md'));

		this._register(this._watcher.onDidChange(async resource => {
			this._documentCache.delete(resource);
		}));

		this._register(this._watcher.onDidDelete(resource => {
			this._documentCache.delete(resource);
		}));

		this._register(vscode.workspace.onDidOpenTextDocument(e => {
			this._documentCache.delete(e.uri);
		}));

		this._register(vscode.workspace.onDidCloseTextDocument(e => {
			this._documentCache.delete(e.uri);
		}));
	}