Merge branch '6.4' into 7.1

* 6.4:
  adding missing 'private'
  just nullable

Author: javiereguiluz

components/serializer.rst

@@ -1486,7 +1486,7 @@ having unique identifiers::
 
     $encoder = new JsonEncoder();
     $defaultContext = [
-        AbstractNormalizer::CIRCULAR_REFERENCE_HANDLER => function (object $object, string $format, array $context): string {
+        AbstractNormalizer::CIRCULAR_REFERENCE_HANDLER => function (object $object, ?string $format, array $context): string {
             return $object->getName();
         },
     ];

security.rst

@@ -2556,7 +2556,7 @@ want to include extra details only for users that have a ``ROLE_SALES_ADMIN`` ro
       class SalesReportManager
       {
     +     public function __construct(
-    +         Security $security,
+    +         private Security $security,
     +     ) {
     +     }