revert usage of empty() as not present in supported versions of lib

Author: Sephster

CHANGELOG.md

@@ -6,7 +6,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ## [Unreleased]
 ### Fixed
-- Use InMemory::empty() instead of InMemory::plainText('') to avoid new empty string exception thrown by lcobucci/jwt (PR #1282)
+- Use string 'empty' instead of InMemory::plainText('') to avoid new empty string exception thrown by lcobucci/jwt (PR #1282)
 
 ## [8.3.4] - released 2022-04-07
 ### Fixed

src/AuthorizationValidators/BearerTokenValidator.php

@@ -70,7 +70,7 @@ private function initJwtConfiguration()
     {
         $this->jwtConfiguration = Configuration::forSymmetricSigner(
             new Sha256(),
-            InMemory::empty()
+            InMemory::plainText('empty', 'empty')
         );
 
         $this->jwtConfiguration->setValidationConstraints(

src/Entities/Traits/AccessTokenTrait.php

@@ -46,7 +46,7 @@ public function initJwtConfiguration()
         $this->jwtConfiguration = Configuration::forAsymmetricSigner(
             new Sha256(),
             InMemory::plainText($this->privateKey->getKeyContents(), $this->privateKey->getPassPhrase() ?? ''),
-            InMemory::empty()
+            InMemory::plainText('empty', 'empty')
         );
     }