title: Symfony3 Form EntityType
body: <p>I am using Symfony3, getting following error when creating form for EntityType::class</p>
  
  <p>My entity namespace
  Project\CoreBundle\Entity\CountryEntity</p>
  
  <pre><code>public function buildForm(FormBuilderInterface $builder, array $options)
  {
      $builder
          -&gt;add('name', TextType::class, ['label' =&gt; 'Name *', 'attr' =&gt; ['data-help'  =&gt; 'enter language name here.']])
          -&gt;add('iso', TextType::class, ['label' =&gt; 'ISO *', 'attr' =&gt; ['data-help'  =&gt; 'enter language code here.']])
          -&gt;add('defaultLanguage', EntityType::class,
              array(
                  'class' =&gt; 'Project\CoreBundle\Entity\CountryEntity'
              )
          )
          -&gt;getForm();
      ;
  }
  </code></pre>
  
  <p>Throws Catchable Fatal Error: Object of class Project\CoreBundle\Entity\CountryEntity could not be converted to string</p>
  
  <p>Any help will be useful, thanks</p>