fix nullable properties

Author: ylebre

src/Entity/Client.php

@@ -20,9 +20,9 @@ class Client implements ClientEntityInterface
      * @param bool $isConfidential
      */
     public function __construct(
-        string $identifier = null,
-        string $name = null,
-        array $redirectUri = null,
+        ?string $identifier = null,
+        ?string $name = null,
+        ?array $redirectUri = null,
         bool $isConfidential = false
     ) {
         $this->isConfidential = $isConfidential;

src/Server.php

@@ -59,9 +59,9 @@ final public function respondToDynamicClientRegistrationRequest(Request $request
 
     final public function respondToAuthorizationRequest(
         Request $request,
-        User $user = null,
-        bool $authorizationApproved = null,
-        callable $callback = null
+        ?User $user = null,
+        ?bool $authorizationApproved = null,
+        ?callable $callback = null
     ) : Response {
         $serverConfig = $this->config->getServer();
         $authorizationServer = $this->authorizationServer;