Merge branch '7.4' into 8.0

* 7.4:
  [Form] Add resource tracking for type extension classes in FormPass
  [Mailer] Postal mailer transport apikey
  [FrameworkBundle] Fix phpstan false-positive about config/reference.php

Author: nicolas-grekas

Resource/ReflectionClassResource.php

@@ -12,6 +12,7 @@
 namespace Symfony\Component\Config\Resource;
 
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+use Symfony\Component\Form\FormTypeExtensionInterface;
 use Symfony\Contracts\Service\ServiceSubscriberInterface;
 
 /**
@@ -211,5 +212,12 @@ private function generateSignature(\ReflectionClass $class): iterable
             yield ServiceSubscriberInterface::class;
             yield print_r($class->name::getSubscribedServices(), true);
         }
+
+        if (interface_exists(FormTypeExtensionInterface::class, false) && $class->isSubclassOf(FormTypeExtensionInterface::class)) {
+            yield FormTypeExtensionInterface::class;
+            foreach ($class->name::getExtendedTypes() as $key => $value) {
+                yield $key.print_r($value, true);
+            }
+        }
     }
 }