adding node to cluster in paralel

AddNewNodes

package io.carousel.it;

import com.google.common.io.Files;
import com.google.common.util.concurrent.Uninterruptibles;
import io.atomix.cluster.Node;
import io.atomix.core.Atomix;
import io.atomix.messaging.Endpoint;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.TimeUnit;

public class AddNewNodes {

    private static final Logger logger = LogManager.getLogger(AddNewNodes.class);

    public static void main(String[] args) {
        Node[] bootstrapNodes = new Node[] {
                Node.builder("server1")
                        .withType(Node.Type.DATA)
                        .withEndpoint(Endpoint.from("127.0.0.1", 5001))
                        .build(),
                Node.builder("server2")
                        .withType(Node.Type.DATA)
                        .withEndpoint(Endpoint.from("127.0.0.1", 5002))
                        .build(),
                Node.builder("server3")
                        .withType(Node.Type.DATA)
                        .withEndpoint(Endpoint.from("127.0.0.1", 5003))
                        .build()
        };

        Atomix atomix1 = createAtomicNode("server1", 5001, bootstrapNodes);
        Atomix atomix2 = createAtomicNode("server2", 5002, bootstrapNodes);
        Atomix atomix3 = createAtomicNode("server3", 5003, bootstrapNodes);

        CompletableFuture
                .allOf(
                        atomix1.start(),
                        atomix2.start(),
                        atomix3.start()
                )
                .whenCompleteAsync((aVoid, throwable) -> logger.info("completed ", throwable))
                .join();

        logger.info("server4/5 joining cluster");

        Atomix atomix4 = createAtomicNode("server4", 5004, bootstrapNodes);
        Atomix atomix5 = createAtomicNode("server5", 5005, bootstrapNodes);

        CompletableFuture
                .allOf(
                        atomix4.start(),
                        atomix5.start()
                )
                .whenCompleteAsync((aVoid, throwable) -> logger.info("completed adding 4 and 5", throwable))
                .join();

        printNodesState(atomix4);
        printNodesState(atomix5);

        Uninterruptibles.sleepUninterruptibly(10, TimeUnit.SECONDS);
        System.exit(0);
    }

    private static void printNodesState(Atomix givenNode) {
        logger.info("it seems {} is running {}.", givenNode.clusterService().getLocalNode().id(),
                givenNode.isRunning());
        for (Node availableNode : givenNode.clusterService().getNodes()) {
            logger.info("node {} is in state {}.", availableNode, availableNode.getState());
        }
    }

    private static Atomix createAtomicNode(String nodeId, int port, Node[] bootstrapNodes) {
        Atomix.Builder builder = Atomix.builder();

        return builder
                .withLocalNode(Node.builder(nodeId)
                        .withType(Node.Type.DATA)
                        .withEndpoint(Endpoint.from("127.0.0.1", port))
                        .build())
                .withDataDirectory(Files.createTempDir())
                .withBootstrapNodes(bootstrapNodes)
                .build();
    }
}

I am using 2.1.0-SNAPSHOT on java8