phpvms/modules/Vacentral/Providers/AppServiceProvider.php

<?php

namespace Modules\Vacentral\Providers;

use App\Services\ModuleService;
use Illuminate\Support\ServiceProvider;

class AppServiceProvider extends ServiceProvider
{
    protected $moduleSvc;

    /**
     * Boot the application events.
     */
    public function boot()
    {
        $this->moduleSvc = app(ModuleService::class);
        $this->registerConfig();
    }

    /**
     * Register config.
     */
    protected function registerConfig()
    {
        $this->publishes([
            __DIR__.'/../Config/config.php' => config_path('vacentral.php'),
        ], 'config');

        $this->mergeConfigFrom(
            __DIR__.'/../Config/config.php', 'vacentral'
        );
    }
}