Lumen : use config constant file from other folder(from parallel laravel folder)

I have laravel and lumen running parallel on a server. and structure is like

var/www/application/laravel var/www/application/lumen Now laravel app is already developed for full fledged website. And lumen folder is being used for webservices. Now there are many constant files in config folder like config>messages.php and I want to reuse those without rewriting it in lumen. But currently all I can see is I can access only lumen constants in lumen, cant access laravel constant file.

Any idea how do I configure lumen code to include laravel config constants file too?

p.s. lumen version : 5.4, laravel version : 5.2

Thanks.