.../src/Functional/EntityResource/EntityResourceTestBase.php   | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
index 9f326bc..7ad570a 100644
--- a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
+++ b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceTestBase.php
@@ -435,11 +435,11 @@ public function testGet() {
     // Finally, assert that the expected 'Link' headers are present.
     $this->assertArrayHasKey('Link', $response->getHeaders());
     $link_relation_type_manager = $this->container->get('plugin.manager.link_relation_type');
-    $expected_link_relation_headers = array_map(function ($rel) use ($link_relation_type_manager) {
-      $definition = $link_relation_type_manager->getDefinition($rel, FALSE);
-      return (!empty($definition['uri']))
-        ? $definition['uri']
-        : $rel;
+    $expected_link_relation_headers = array_map(function ($relation_name) use ($link_relation_type_manager) {
+      $link_relation_type = $link_relation_type_manager->createInstance($relation_name);
+      return $link_relation_type->isRegistered()
+        ? $link_relation_type->getRegisteredName()
+        : $link_relation_type->getExtensionUri();
     }, array_keys($this->entity->getEntityType()->getLinkTemplates()));
     $parse_rel_from_link_header = function ($value) use ($link_relation_type_manager) {
       $matches = [];