minor #12408 Update events.rst (ddegasperi)

This PR was submitted for the master branch but it was merged into the 4.3 branch instead (closes #12408).

Discussion
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Update events.rst

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Commits
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c00b90d Update events.rst

Author: javiereguiluz

reference/events.rst

@@ -87,6 +87,8 @@ Typically, this is used to map URL routing parameters to their corresponding
 named arguments; or pass the current request when the ``Request`` type-hint is
 found::
 
+    use Symfony\Component\HttpKernel\Event\ControllerArgumentsEvent;
+
     public function onKernelControllerArguments(ControllerArgumentsEvent $event)
     {
         // ...
@@ -149,6 +151,8 @@ This event is dispatched after the controller or any ``kernel.view`` listener
 returns a ``Response`` object. It's useful to modify or replace the response
 before sending it back (e.g. add/modify HTTP headers, add cookies, etc.)::
 
+    use Symfony\Component\HttpKernel\Event\ResponseEvent;
+
     public function onKernelResponse(ResponseEvent $event)
     {
         $response = $event->getResponse();
@@ -176,6 +180,8 @@ This event is dispatched after the ``kernel.response`` event. It's useful to res
 the global state of the application (for example, the translator listener resets
 the translator's locale to the one of the parent request)::
 
+    use Symfony\Component\HttpKernel\Event\FinishRequestEvent;
+
     public function onKernelFinishRequest(FinishRequestEvent $event)
     {
         if (null === $parentRequest = $this->requestStack->getParentRequest()) {