diff --git a/src/Normalizer/JsonApiDocumentTopLevelNormalizer.php b/src/Normalizer/JsonApiDocumentTopLevelNormalizer.php
index fc46e8e..45de4b9 100644
--- a/src/Normalizer/JsonApiDocumentTopLevelNormalizer.php
+++ b/src/Normalizer/JsonApiDocumentTopLevelNormalizer.php
@@ -317,7 +317,7 @@ class JsonApiDocumentTopLevelNormalizer extends NormalizerBase implements Denorm
     }
     // Ensure that the client provided ID is a valid UUID.
     if (isset($document['data']['id']) && !Uuid::isValid($document['data']['id'])) {
-      throw new AccessDeniedHttpException('IDs must by properly generated and formatted UUID as described in RFC 4122.');
+      throw new AccessDeniedHttpException('IDs should be properly generated and formatted UUIDs as described in RFC 4122.');
     }
   }
 
diff --git a/tests/src/Unit/Normalizer/JsonApiDocumentTopLevelNormalizerTest.php b/tests/src/Unit/Normalizer/JsonApiDocumentTopLevelNormalizerTest.php
index aedd797..f007c98 100644
--- a/tests/src/Unit/Normalizer/JsonApiDocumentTopLevelNormalizerTest.php
+++ b/tests/src/Unit/Normalizer/JsonApiDocumentTopLevelNormalizerTest.php
@@ -140,9 +140,9 @@ class JsonApiDocumentTopLevelNormalizerTest extends UnitTestCase {
         [
           'uuid' => '0676d1bf-55b3-4bbc-9fbc-3df10f4599d5',
           'field_dummy' => [
-          [
-            'target_id' => 1,
-          ],
+            [
+              'target_id' => 1,
+            ],
           ],
         ],
       ],
@@ -170,12 +170,8 @@ class JsonApiDocumentTopLevelNormalizerTest extends UnitTestCase {
         [
           'uuid' => '535ba297-8d79-4fc1-b0d6-dc2f047765a1',
           'field_dummy' => [
-          [
-            'target_id' => 1,
-          ],
-          [
-            'target_id' => 2,
-          ],
+            ['target_id' => 1],
+            ['target_id' => 2],
           ],
         ],
       ],
@@ -204,13 +200,11 @@ class JsonApiDocumentTopLevelNormalizerTest extends UnitTestCase {
         [
           'uuid' => '535ba297-8d79-4fc1-b0d6-dc2f047765a1',
           'field_dummy' => [
-          [
-            'target_id' => 1,
-            'foo' => 'bar',
-          ],
-          [
-            'target_id' => 2,
-          ],
+            [
+              'target_id' => 1,
+              'foo' => 'bar',
+            ],
+            ['target_id' => 2],
           ],
         ],
       ],
@@ -229,17 +223,14 @@ class JsonApiDocumentTopLevelNormalizerTest extends UnitTestCase {
    * @dataProvider denormalizeUuidProvider
    */
   public function testDenormalizeUuid($id, $expect_exception) {
-    $data = [
-      'data' => [
-        'type' => 'node--article',
-        'id' => $id,
-      ],
-    ];
+    $data['data'] = (isset($id)) ?
+      ['type' => 'node--article', 'id' => $id] :
+      ['type' => 'node--article'];
 
     if ($expect_exception) {
       $this->setExpectedException(
         AccessDeniedHttpException::class,
-        'IDs must by properly generated and formatted UUID as described in RFC 4122.'
+        'IDs should be properly generated and formatted UUIDs as described in RFC 4122.'
       );
     }
 
@@ -251,7 +242,12 @@ class JsonApiDocumentTopLevelNormalizerTest extends UnitTestCase {
       ),
     ]);
 
-    $this->assertSame($id, $denormalized['uuid']);
+    if (isset($id)) {
+      $this->assertSame($id, $denormalized['uuid']);
+    }
+    else {
+      $this->assertArrayNotHasKey('uuid', $denormalized);
+    }
   }
 
   /**
@@ -260,7 +256,8 @@ class JsonApiDocumentTopLevelNormalizerTest extends UnitTestCase {
   public function denormalizeUuidProvider() {
     return [
       'valid' => ['76dd5c18-ea1b-4150-9e75-b21958a2b836', FALSE],
-      'empty' => ['', TRUE],
+      'missing' => [NULL, FALSE],
+      'invalid_empty' => ['', TRUE],
       'invalid_alpha' => ['invalid', TRUE],
       'invalid_numeric' => [1234, TRUE],
       'invalid_alphanumeric' => ['abc123', TRUE],