The Lagom service client components.
The name of the topic publisher.
Since topic publishers don't actually provide any components, they just consume a LagomServer and publish the
topics they find there, this can be used to signal that a topic publisher has been provided to publish
topics, so that the LagomServerComponents can detect a misconfiguration where one hasn't been provided.
The name of the topic publisher that has published topics, if one has been provided.