Replace $supportedInterfaceOrClass with getSupportedTypes()

src/Normalizer/RefreshTokenEntityNormalizer.php

@@ -3,16 +3,10 @@
 namespace Drupal\simple_oauth\Normalizer;
 
 use Drupal\serialization\Normalizer\NormalizerBase;
+use League\OAuth2\Server\Entities\RefreshTokenEntityInterface;
 
 class RefreshTokenEntityNormalizer extends NormalizerBase implements TokenEntityNormalizerInterface {
 
-  /**
-   * The interface or class that this Normalizer supports.
-   *
-   * @var string|array
-   */
-  protected $supportedInterfaceOrClass = '\League\OAuth2\Server\Entities\RefreshTokenEntityInterface';
-
   /**
    * {@inheritdoc}
    */
@@ -24,4 +18,10 @@ class RefreshTokenEntityNormalizer extends NormalizerBase implements TokenEntity
     ];
   }
 
+  public function getSupportedTypes(?String $format = NULL): array {
+    return [
+      RefreshTokenEntityInterface::class => TRUE,
+    ];
+  }
+
 }