Merge branch '5.4' into 6.2

* 5.4:
  relax assertions for ICU 72.1
  [Validator] Fix regression with class metadatada on parent classes
  [VarExporter] Fix exporting classes with __serialize() but not __unserialize()
  [HttpFoundation][HttpKernel] Fix deprecations when `Content-Type` is `null`

Author: derrabus

Validator/DoctrineLoader.php

@@ -105,7 +105,7 @@ public function loadClassMetadata(ClassMetadata $metadata): bool
                 if (isset($mapping['originalClass']) && !str_contains($mapping['declaredField'], '.')) {
                     $metadata->addPropertyConstraint($mapping['declaredField'], new Valid());
                     $loaded = true;
-                } elseif (property_exists($className, $mapping['fieldName'])) {
+                } elseif (property_exists($className, $mapping['fieldName']) && (!$doctrineMetadata->isMappedSuperclass || $metadata->getReflectionClass()->getProperty($mapping['fieldName'])->isPrivate())) {
                     $metadata->addPropertyConstraint($mapping['fieldName'], new Length(['max' => $mapping['length']]));
                     $loaded = true;
                 }