CompletableFuture<Consumer> existingConsumerFuture = consumers.putIfAbsent(consumerId, consumerFuture);
CompletableFuture<Producer> existingProducerFuture = producers.putIfAbsent(producerId, producerFuture);
CompletableFuture<Consumer> existingConsumerFuture = consumers.putIfAbsent(consumerId, consumerFuture);
CompletableFuture<Producer> existingProducerFuture = producers.putIfAbsent(producerId, producerFuture);