[SecurityGuard] Implement PostAuthenticationGuardToken::getFirewallName().

Author: derrabus

src/Symfony/Component/Security/Guard/Token/PostAuthenticationGuardToken.php

@@ -69,6 +69,11 @@ public function getProviderKey()
         return $this->providerKey;
     }
 
+    public function getFirewallName(): string
+    {
+        return $this->getProviderKey();
+    }
+
     /**
      * {@inheritdoc}
      */