Route::prefix('message')->group(function () {
    Route::get('/', 'CustomMessageController@index');
});

Route::prefix('message')->group(function () {
    Route::get('/', 'Http/Controllers/CustomMessageController@index');
});

$this->app->make('DevdojoCalculatorCalculatorController');

<?php

namespace Alive2212LaravelMessageServiceProviders;

use IlluminateSupportFacadesRoute;
use IlluminateFoundationSupportProvidersRouteServiceProvider as ServiceProvider;

class AliveLaravelMessageServiceRouteServiceProvider extends ServiceProvider
{
    protected $namespace = 'Alive2212LaravelMessageServiceHttpControllers';

    public function boot()
    {
    parent::boot();
    }

    public function map()
    {
    $this->mapApiRoutes();
    }

    protected function mapApiRoutes()
    {
    Route::prefix('alive_api')
         ->namespace($this->namespace)
         ->group(__DIR__.'/../../routes/api.php');
    }
}

public function boot()
{
    $this->app->register(AliveLaravelMessageServiceRouteServiceProvider::class);
}

Route::prefix('message')->group(function () {
    Route::get('/', 'CustomMessageController@index');
});

namespace Alive2212LaravelMessageServiceHttpControllers;

use Alive2212LaravelMessageServiceHttpControllersController;
use Alive2212LaravelMessageServiceMessage;
use IlluminateHttpRequest;

class CustomMessageController extends Controller
{
    protected $model;

    public function __construct()
    {
    $this->model = new Message();
    }

    public function index(Request $request)
    {
        return "the is my package index controller";
    }

}

public function register()
    {
        include __DIR__ . '/routes.php';
    }