reworked the Mediator pattern

Behavioral/Mediator/UserRepository.php

@@ -0,0 +1,11 @@
+<?php declare(strict_types=1);
+
+namespace DesignPatterns\Behavioral\Mediator;
+
+class UserRepository extends Colleague
+{
+    public function getUserName(string $user): string
+    {
+        return 'User: ' . $user;
+    }
+}