do not overwrite an application's default serialization context

Author: xabbuh

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php

@@ -1848,9 +1848,15 @@ private function registerSerializerConfiguration(array $config, ContainerBuilder
             $container->getDefinition('serializer.name_converter.metadata_aware')->setArgument(1, new Reference($config['name_converter']));
         }
 
+        $defaultContext = $config['default_context'] ?? [];
+
+        if ($defaultContext) {
+            $container->setParameter('serializer.default_context', $defaultContext);
+        }
+
         if (isset($config['circular_reference_handler']) && $config['circular_reference_handler']) {
             $arguments = $container->getDefinition('serializer.normalizer.object')->getArguments();
-            $context = ($arguments[6] ?? []) + ['circular_reference_handler' => new Reference($config['circular_reference_handler'])];
+            $context = ($arguments[6] ?? $defaultContext) + ['circular_reference_handler' => new Reference($config['circular_reference_handler'])];
             $container->getDefinition('serializer.normalizer.object')->setArgument(5, null);
             $container->getDefinition('serializer.normalizer.object')->setArgument(6, $context);
         }
@@ -1860,10 +1866,6 @@ private function registerSerializerConfiguration(array $config, ContainerBuilder
             $defaultContext += ['max_depth_handler' => new Reference($config['max_depth_handler'])];
             $container->getDefinition('serializer.normalizer.object')->replaceArgument(6, $defaultContext);
         }
-
-        if (isset($config['default_context']) && $config['default_context']) {
-            $container->setParameter('serializer.default_context', $config['default_context']);
-        }
     }
 
     private function registerPropertyInfoConfiguration(ContainerBuilder $container, PhpFileLoader $loader)

src/Symfony/Bundle/FrameworkBundle/Tests/Fixtures/Serializer/CircularReferenceHandler.php

@@ -0,0 +1,19 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Bundle\FrameworkBundle\Tests\Fixtures\Serializer;
+
+class CircularReferenceHandler
+{
+    public function __invoke()
+    {
+    }
+}

src/Symfony/Bundle/FrameworkBundle/Tests/Functional/app/Serializer/config.yml

@@ -4,6 +4,7 @@ imports:
 framework:
     serializer:
         enabled: true
+        circular_reference_handler: Symfony\Bundle\FrameworkBundle\Tests\Fixtures\Serializer\CircularReferenceHandler
         default_context:
             enable_max_depth: true
             fake_context_option: foo
@@ -57,3 +58,5 @@ services:
     serializer.encoder.csv.alias:
         alias: serializer.encoder.csv
         public: true
+
+    Symfony\Bundle\FrameworkBundle\Tests\Fixtures\Serializer\CircularReferenceHandler: ~