.../tests/src/Functional/Rest/EntityTestMapFieldResourceTestBase.php | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/core/modules/system/tests/modules/entity_test/tests/src/Functional/Rest/EntityTestMapFieldResourceTestBase.php b/core/modules/system/tests/modules/entity_test/tests/src/Functional/Rest/EntityTestMapFieldResourceTestBase.php
index 6e62d9a..e9ac106 100644
--- a/core/modules/system/tests/modules/entity_test/tests/src/Functional/Rest/EntityTestMapFieldResourceTestBase.php
+++ b/core/modules/system/tests/modules/entity_test/tests/src/Functional/Rest/EntityTestMapFieldResourceTestBase.php
@@ -78,6 +78,11 @@ protected function createEntity() {
   protected function getExpectedNormalizedEntity() {
     $author = User::load(0);
     return [
+      'uuid' => [
+        [
+          'value' => $this->entity->uuid(),
+        ],
+      ],
       'id' => [
         [
           'value' => 1,