title: Cannot autowire service
body: <p>I am trying to implement UserManager from FOSUserBundle (Symfony3.4).</p>
  
  <p>Service/Register.php</p>
  
  <pre><code>&lt;?php
  
  namespace AppBundle\Service;
  
  use FOS\UserBundle\Model\UserManager;
  
  
  class Register
  {
      private $userManager;
  
      public function __construct(UserManager $userManager)
      {
          $this-&gt;userManager = $userManager;
      }
  
      public function register() {
          $user = $this-&gt;userManager-&gt;findUserByUsernameOrEmail('aaa@gmail.clom');
          if($user){
              return false;
          }
          return true;
      }
  }
  </code></pre>
  
  <p>When I try call this method I get:</p>
  
  <blockquote>
    <p>Cannot autowire service "AppBundle\Service\Register": argument "$userManager" of method "__construct()" references class "FOS\UserBundle\Model\UserManager" but no such service exists. You should maybe alias this class to the existing "fos_user.user_manager.default" service.</p>
  </blockquote>
  
  <p>What should I do now?</p>