Use NullablePropertyTrait when describing an object property

PropertyDescriber/ObjectPropertyDescriber.php

@@ -20,13 +20,14 @@
 
 class ObjectPropertyDescriber implements PropertyDescriberInterface, ModelRegistryAwareInterface
 {
+    use NullablePropertyTrait;
     use ModelRegistryAwareTrait;
 
     public function describe(array $types, OA\Schema $property, array $groups = null, ?OA\Schema $schema = null)
     {
         $type = new Type(
             $types[0]->getBuiltinType(),
-            false,
+            $types[0]->isNullable(),
             $types[0]->getClassName(),
             $types[0]->isCollection(),
             // BC layer for symfony < 5.3
@@ -36,9 +37,10 @@ public function describe(array $types, OA\Schema $property, array $groups = null
                 $types[0]->getCollectionValueType()
         ); // ignore nullable field
 
+        $this->setNullableProperty($type, $property, $schema);
+
         if ($types[0]->isNullable()) {
             $weakContext = Util::createWeakContext($property->_context);
-            $property->nullable = true;
             $property->allOf = [new OA\Schema(['ref' => $this->modelRegistry->register(new Model($type, $groups)), '_context' => $weakContext])];
 
             return;