firefly-iii/app/Providers/BroadcastServiceProvider.php

<?php
/**
 * BroadcastServiceProvider.php
 * Copyright (C) 2016 thegrumpydictator@gmail.com
 *
 * This software may be modified and distributed under the terms
 * of the MIT license.  See the LICENSE file for details.
 */
declare(strict_types = 1);

namespace FireflyIII\Providers;

use Illuminate\Support\Facades\Broadcast;
use Illuminate\Support\ServiceProvider;

/**
 * Class BroadcastServiceProvider
 *
 * @package FireflyIII\Providers
 */
class BroadcastServiceProvider extends ServiceProvider
{
    /**
     * Bootstrap any application services.
     *
     * @return void
     */
    public function boot()
    {
        Broadcast::routes();

        /*
         * Authenticate the user's personal channel...
         */
        Broadcast::channel(
            'App.User.*', function ($user, $userId) {
            return (int)$user->id === (int)$userId;
        }
        );
    }
}