src/vs/workbench/common/views.ts/ViewsRegistry/registerViewWelcomeContent2
class ViewsRegistry:	registerViewWelcomeContent2<TKey>(id: string, viewContentMap: Map<TKey, IViewContentDescriptor>): Map<TKey, IDisposable> {
		const disposables = new Map<TKey, IDisposable>();

		for (const [key, content] of viewContentMap) {
			this._viewWelcomeContents.add(id, content);

			disposables.set(key, toDisposable(() => {
				this._viewWelcomeContents.delete(id, content);
				this._onDidChangeViewWelcomeContent.fire(id);
			}));
		}
		this._onDidChangeViewWelcomeContent.fire(id);

		return disposables;
	}