Class Level @SendTo

When @SendTo will be handled?

If @SendTo is present on valid class with class-level @KafkaListener or @KafkaListeners, and non-void @KafkaHandler is present on one of its methods

@KafkaListener(topics = {"messages.blue"})
@KafkaListener(topics = {"messages.green"})
@SendTo({"messages.*.replies", "messages.*.replies-2"})
public class MultiMessagesListener {

    @KafkaHandler
    public String listen(Object message) {}

}

When @SendTo will be ignored?

Empty @SendTo

When @SendTo annotation is empty

@KafkaListener(topics = {"messages.blue"})
@KafkaListener(topics = {"messages.green"})
@SendTo
public class MultiMessagesListener {

    @KafkaHandler
    public String listen(Object message) {}

}

Only void @KafkaHandler

When all @KafkaHandler methods are void

@KafkaListener(topics = {"messages.blue"})
@KafkaListener(topics = {"messages.green"})
@SendTo({"messages.*.replies", "messages.*.replies-2"})
public class MultiMessagesListener {

    @KafkaHandler
    public void listen(Object message) {}

}