Kafka Extension for isolated mode not sending key

Hi 👋

i am currently working on switching a kafka producer in-proc function towards a out-proc function. During the switch we noticed,
that the produced message is not transported the same way as before

With the old method we used the KafkaEventData object and have seen a message on the kafka with a key and a value.

With the new binding for isolated, there was no KafkaEventData object any longer, so we decided to use our own class with just a key and a value property. Now the problem is, that we can see this message on the topic, but the message is only shown with a value. The new class is packed inside.

What can i do to make it work like before?

I've seen that there was previously a class Message from the confluent package used, but i was not able to find the new implementation for the communication against kafka.