Reactor.kt

fun flux() =
    Flux.mergeSequential(getMonoResponse(100), getMonoResponse(200))
        .collectList()
        .flatMap { v ->
            return@flatMap getMonoResponse(300)
                .map { v2 ->
                    v.add(v2)
                    return@map v
                }
        }.flatMap { v ->
            val period = v[2]["totalTimeMillis"].parseLong()
            Flux.mergeSequential(getMonoResponse(period + 100), getMonoResponse(period + 200))
                .collectList()
                .map { v2 ->
                    v.addAll(v2)
                    return@map v
                }
        }.map { v ->
            mapOf(
                "delay100res" to v[0]["totalTimeMillis"],
                "delay200res" to v[1]["totalTimeMillis"],
                "delay300res" to v[2]["totalTimeMillis"],
                "delay400res" to v[3]["totalTimeMillis"],
                "delay500res" to v[4]["totalTimeMillis"]
            )
        }

private fun getMonoResponse(ms: Long) = webClient.get()
    .uri("http://$domain:8888/delay/ms/$ms")
    .retrieve()
    .bodyToMono(object : ParameterizedTypeReference<Map<*, *>>() {})