update code

app/Providers/EventServiceProvider.php

@@ -0,0 +1,48 @@
+<?php
+
+namespace App\Providers;
+
+use Illuminate\Auth\Events\Registered;
+use Illuminate\Auth\Listeners\SendEmailVerificationNotification;
+use Illuminate\Foundation\Support\Providers\EventServiceProvider as ServiceProvider;
+use Illuminate\Support\Facades\Event;
+use App\Events\{
+    UserViewedDocument,
+    UsersReceivedDocument,
+};
+use App\Listeners\{
+    UpdateReceiverToSeen,
+    NotifyDocumentReceivedToUsers,
+};
+
+class EventServiceProvider extends ServiceProvider
+{
+    /**
+     * The event listener mappings for the application.
+     *
+     * @var array
+     */
+    protected $listen = [
+        Registered::class => [
+            SendEmailVerificationNotification::class,
+        ],
+        UserViewedDocument::class => [
+            UpdateReceiverToSeen::class,
+        ],
+        UsersReceivedDocument::class => [
+            NotifyDocumentReceivedToUsers::class,
+        ],
+    ];
+
+    /**
+     * Register any events for your application.
+     *
+     * @return void
+     */
+    public function boot()
+    {
+        parent::boot();
+
+        \App\Entities\User::observe(\App\Observers\UserObserver::class);
+    }
+}