sendCloudEvent.java

final SubmissionPublisher<CloudEvent> emitter = new SubmissionPublisher<>();

@Outgoing("to-stream")
public PublisherBuilder<CloudEvent> registerEmitter() {
    return ReactiveStreams.fromPublisher(FlowAdapters.toPublisher(emitter));
}

@POST
@Path("/send/{msg}")
public void send(@PathParam("msg") String payload) {
    CloudEvent cloudEvent = eventTemplate
            .withId(UUID.randomUUID().toString())
            .withData(MediaType.TEXT_PLAIN, payload.getBytes())
            .build();
    emitter.submit(cloudEvent);
}