Added kid header in id token

Author: DarthLegiON

src/IdTokenResponse.php

@@ -30,12 +30,19 @@ class IdTokenResponse extends BearerTokenResponse
      */
     protected $claimExtractor;
 
+    /**
+     * @var string|null
+     */
+    protected $keyIdentifier;
+    
     public function __construct(
         IdentityProviderInterface $identityProvider,
-        ClaimExtractor $claimExtractor
+        ClaimExtractor $claimExtractor,
+        ?string $keyIdentifier = null
     ) {
         $this->identityProvider = $identityProvider;
         $this->claimExtractor   = $claimExtractor;
+        $this->keyIdentifier   = $keyIdentifier;
     }
 
     protected function getBuilder(AccessTokenEntityInterface $accessToken, UserEntityInterface $userEntity)
@@ -87,6 +94,10 @@ protected function getExtraParams(AccessTokenEntityInterface $accessToken)
             $builder = $builder->withClaim($claimName, $claimValue);
         }
 
+        if ($this->keyIdentifier !== null) {
+            $builder = $builder->withHeader('kid', $keyIdentifier);
+        }
+
         if (
             method_exists($this->privateKey, 'getKeyContents')
             && !empty($this->privateKey->getKeyContents())