minor #9763 Update argument_value_resolver.rst (ddegasperi)

This PR was submitted for the master branch but it was merged into the 3.4 branch instead (closes #9763).

Discussion
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Update argument_value_resolver.rst

Add missing class imports

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Commits
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5b49c7b Update argument_value_resolver.rst

Author: javiereguiluz

controller/argument_value_resolver.rst

@@ -96,8 +96,11 @@ retrieved from the token storage::
     namespace AppBundle\ArgumentResolver;
 
     use AppBundle\Entity\User;
+    use Symfony\Component\HttpFoundation\Request;
     use Symfony\Component\HttpKernel\Controller\ArgumentValueResolverInterface;
+    use Symfony\Component\HttpKernel\ControllerMetadata\ArgumentMetadata;
     use Symfony\Component\Security\Core\Authentication\Token\Storage\TokenStorageInterface;
+    use Symfony\Component\Security\Core\Authentication\Token\TokenInterface;
 
     class UserValueResolver implements ArgumentValueResolverInterface
     {