core/modules/rest/src/RequestHandler.php                         | 1 +
 core/modules/rest/tests/src/Kernel/RequestHandlerTest.php        | 9 +++------
 .../serialization/tests/src/Kernel/EntitySerializationTest.php   | 6 +++++-
 3 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/core/modules/rest/src/RequestHandler.php b/core/modules/rest/src/RequestHandler.php
index 11a578c..905af1a 100644
--- a/core/modules/rest/src/RequestHandler.php
+++ b/core/modules/rest/src/RequestHandler.php
@@ -192,6 +192,7 @@ protected function createArgumentResolver(RouteMatchInterface $route_match, $uns
     $wildcard_arguments[] = $request;
     if (isset($unserialized)) {
       $wildcard_arguments[] = $unserialized;
+      $raw_route_arguments['data'] = $unserialized;
     }
 
     return new ArgumentsResolver($raw_route_arguments, $upcasted_route_arguments, $wildcard_arguments);
diff --git a/core/modules/rest/tests/src/Kernel/RequestHandlerTest.php b/core/modules/rest/tests/src/Kernel/RequestHandlerTest.php
index 7d38a97..4ede7e4 100644
--- a/core/modules/rest/tests/src/Kernel/RequestHandlerTest.php
+++ b/core/modules/rest/tests/src/Kernel/RequestHandlerTest.php
@@ -42,10 +42,7 @@ class RequestHandlerTest extends KernelTestBase {
   public function setUp() {
     parent::setUp();
     $this->entityStorage = $this->prophesize(EntityStorageInterface::class);
-    $config_factory = $this->prophesize(ConfigFactoryInterface::class);
-    $config_factory->get('rest.settings')
-      ->willReturn($this->prophesize(ImmutableConfig::class)->reveal());
-    $this->requestHandler = new RequestHandler($this->entityStorage->reveal(), $config_factory->reveal());
+    $this->requestHandler = new RequestHandler($this->entityStorage->reveal());
     $this->requestHandler->setContainer($this->container);
   }
 
@@ -98,9 +95,9 @@ public function testHandle() {
  */
 class StubRequestHandlerResourcePlugin extends ResourceBase {
 
-  public function get($example, Request $request) {}
+  public function get($example = NULL, Request $request) {}
   public function post() {}
-  public function patch($example_original, Request $request) {}
+  public function patch($example_original = NULL, Request $request) {}
   public function delete() {}
 
 }
diff --git a/core/modules/serialization/tests/src/Kernel/EntitySerializationTest.php b/core/modules/serialization/tests/src/Kernel/EntitySerializationTest.php
index 5bde06b..81140d9 100644
--- a/core/modules/serialization/tests/src/Kernel/EntitySerializationTest.php
+++ b/core/modules/serialization/tests/src/Kernel/EntitySerializationTest.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\Tests\serialization\Kernel;
 
+use Drupal\Component\Datetime\DateTimePlus;
 use Drupal\Component\Utility\SafeMarkup;
 use Drupal\entity_test\Entity\EntityTestMulRev;
 use Drupal\Tests\rest\Functional\BcTimestampNormalizerUnixTestTrait;
@@ -189,7 +190,10 @@ public function testSerialize() {
 
     // Generate the expected xml in a way that allows changes to entity property
     // order.
-    $expected_created = $this->formatExpectedTimestampItemValues($this->entity->created->value);
+    $expected_created = [
+      'value' => DateTimePlus::createFromTimestamp($this->entity->created->value, 'UTC')->format(\DateTime::RFC3339),
+      'format' => \DateTime::RFC3339,
+    ];
 
     $expected = [
       'id' => '<id><value>' . $this->entity->id() . '</value></id>',