src/vs/platform/diagnostics/node/diagnosticsService.ts/DiagnosticsService/getWorkspaceFileExtensions
class DiagnosticsService:	public async getWorkspaceFileExtensions(workspace: IWorkspace): Promise<{ extensions: string[] }> {
		const items = new Set<string>();
		for (const { uri } of workspace.folders) {
			const folderUri = URI.revive(uri);
			if (folderUri.scheme !== Schemas.file) {
				continue;
			}
			const folder = folderUri.fsPath;
			try {
				const stats = await collectWorkspaceStats(folder, ['node_modules', '.git']);
				stats.fileTypes.forEach(item => items.add(item.name));
			} catch { }
		}
		return { extensions: [...items] };
	}