How to send push notifications to multiple devices using Migrate from legacy FCM APIs to HTTP v1 in laravel?

i send fcm token in array format but i getting error “field”:”message”,”description”:”Invalid JSON payload received. Unknown name “tokens” at ‘message’: Cannot find field.”

$fields = [
           'message' => [
           'tokens' => $fcmIds,
           'notification' => $notificationData,
           'data' => $dataPayload,
            ],
          ];

i send like this FCM token in array format.