Drop code for < Symfony 3.4

ManagerRegistry.php

@@ -5,12 +5,10 @@
 namespace Doctrine\Bundle\MongoDBBundle;
 
 use Doctrine\ODM\MongoDB\MongoDBException;
+use Psr\Container\ContainerInterface;
 use Symfony\Bridge\Doctrine\ManagerRegistry as BaseManagerRegistry;
-use Symfony\Component\DependencyInjection\ContainerAwareTrait;
-use Symfony\Component\DependencyInjection\ContainerInterface;
 
 use function array_keys;
-use function class_uses;
 
 class ManagerRegistry extends BaseManagerRegistry
 {
@@ -22,14 +20,7 @@ class ManagerRegistry extends BaseManagerRegistry
      */
     public function __construct($name, array $connections, array $managers, $defaultConnection, $defaultManager, $proxyInterfaceName, ?ContainerInterface $container = null)
     {
-        $parentTraits = class_uses(parent::class);
-        if (isset($parentTraits[ContainerAwareTrait::class])) {
-            // this case should be removed when Symfony 3.4 becomes the lowest supported version
-            // and then also, the constructor should type-hint Psr\Container\ContainerInterface
-            $this->setContainer($container);
-        } else {
-            $this->container = $container;
-        }
+        $this->container = $container;
 
         parent::__construct($name, $connections, $managers, $defaultConnection, $defaultManager, $proxyInterfaceName);
     }