What Validation Classes Do I need To Import

Hi I'm trying to add a custom validation to Services and I get errors for missing classes the error is - Class 'Validation' not found

<?php

namespace App\Providers;

use Illuminate\Support\ServiceProvider;
use Illuminate\Validation\Factory;
use App\Validator;

class AppServiceProvider extends ServiceProvider
{
    /**
     * Bootstrap any application services.
     *
     * @return void
     */
    public function boot()
    {        

        \Validator::resolver(function($translator, $data, $rules, $messages)
        {
            //error here
            return new \Validation($translator, $data, $rules, $messages);
        });
    }

    /**
     * Register any application services.
     *
     * @return void
     */
    public function register()
    {
        //
    }
}

via Chebli Mohamed