spring-boot - Convert Spring Cloud Stream to use reactive cloud function

Question

Currently I have Spring Boot application which is something like this.

@Component
@EnableBinding(Source::class)
class EmailMessageProducer(private val source: Source) {

    suspend fun send(textMessage: TextMessage) {

        source.output().send(
            MessageBuilder.withPayload(textMessage).setHeader("service", "test").build()
        )
    }
}

I would like to use Spring Cloud Function here using reactive pattern.

Furthermore, is my current solution non blocking? I am asking this because this is my first time using Kotlin coroutine in this context.

Java solution works for me as well since I am just trying to understand the concept here.