Lagom service on startup requires to publish message on Kafka topic

Hi ,
I have a use case that requires Lagom services on startup to tell other services (non Lagom services) that it is up and requires some data from other services. How I am thinking of approaching this is via KAFKA. I have a KAFKA instance which is being shared by all services (Lagom and non-Lagom). I am able to read from the KAFKA topic but I don’t know how to publish a random message on startup of the Lagom service ,so that other services can start publishing to Kafka . In the documentation I read it says that only persistence events can be published (this is what I understood) Lagom - Message Broker API .Is there some other way of achieving the same ?? Can someone please guide me??