title: Symfony2 Could not load type EntityType
body: <p>I have a problem when I'm trying to create an EntityType field in my Symfony2 form type.</p>
  
  <p>This is the piece of code from the official EntityType reference in Symfony2 manual:</p>
  
  <pre><code>use Symfony\Bridge\Doctrine\Form\Type\EntityType; 
  
  ...
  
  $builder-&gt;add('users', EntityType::class, array(
          'class' =&gt; 'AppBundle:User',
          'choice_label' =&gt; 'username',
      ));
  </code></pre>
  
  <p>Going back to the browser I'm getting the <code>Could not load type "Symfony\Bridge\Doctrine\Form\Type\EntityType"</code> error.</p>
  
  <p>The EntityType class exist in the given namespespace. </p>
  
  <p>Do I need to get some aditional extensions for this field type?</p>