.../EntityResource/ContactForm/ContactFormResourceTestBase.php   | 9 ++++++++-
 .../src/Functional/EntityResource/EntityResourceTestBase.php     | 3 +++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/core/modules/rest/tests/src/Functional/EntityResource/ContactForm/ContactFormResourceTestBase.php b/core/modules/rest/tests/src/Functional/EntityResource/ContactForm/ContactFormResourceTestBase.php
index 23464bf..51e297a 100644
--- a/core/modules/rest/tests/src/Functional/EntityResource/ContactForm/ContactFormResourceTestBase.php
+++ b/core/modules/rest/tests/src/Functional/EntityResource/ContactForm/ContactFormResourceTestBase.php
@@ -51,6 +51,10 @@ protected function createEntity() {
       'label' => 'Llama',
       'message' => 'Let us know what you think about llamas',
       'reply' => 'Llamas are indeed awesome!',
+      'recipients' => [
+        'llama@example.com',
+        'contact@example.com',
+      ],
     ]);
     $contact_form->save();
 
@@ -67,7 +71,10 @@ protected function getExpectedNormalizedEntity() {
       'label' => 'Llama',
       'langcode' => 'en',
       'message' => 'Let us know what you think about llamas',
-      'recipients' => [],
+      'recipients' => [
+        'llama@example.com',
+        'contact@example.com',
+      ],
       'redirect' => NULL,
       'reply' => 'Llamas are indeed awesome!',
       'status' => TRUE,
diff --git a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
index 6efdde1..fe4ebb8 100644
--- a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
+++ b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
@@ -1274,6 +1274,9 @@ protected function assertNormalizationEdgeCases($method, Url $url, array $reques
    */
   protected function getEntityResourceUrl() {
     $has_canonical_url = $this->entity->hasLinkTemplate('canonical');
+    // Note that the 'canonical' link relation type must be specified explicitly
+    // in the call to ::toUrl(). 'canonical' is the default for
+    // \Drupal\Core\Entity\Entity::toUrl(), but ConfigEntityBase overrides this.
     return $has_canonical_url ? $this->entity->toUrl('canonical') : Url::fromUri('base:entity/' . static::$entityTypeId . '/' . $this->entity->id());
   }