Multilevel menu in Laravel Voyager admin panel not woking

I am using Voyager admin package in my Laravel app. I tried to make 2 level dropdown menu like this:

Pages

  -page1

  -page2

    -page2A

    -page2B

but it seems that Voyager does not support 2 or more than 2 level menu dropdown. So i searched on the internet and i found only one solution for this on github.This one
I tried to make change like above solution but it still it does not work. Anybody had this issue?

via Chebli Mohamed