How to launch a new openstack instance in Java?

I was trying to launch new open-stack instance in Java by referring below URL.

https://help.dreamhost.com/hc/en-us/articles/216456877-How-to-launch-and-delete-OpenStack-instances-using-Java-and-Jclouds

And here is how my createInstance method looks like :-

public void createInstance(String instanceName) {
    for (String region : regions) {
        ServerApi serverApi = novaApi.getServerApi(region);
        System.out.println("server api : " + serverApi.toString());
        String imageId = "7d246e9a-dd2a-4342-97f7-32accd0f9c35";
        String flavorId = "8041379d-7261-401d-90cf-e2d97184fe94";

        /*Launch an instance*/
        ServerCreated ser = serverApi.create(instanceName, imageId, flavorId);

        Server server = serverApi.get(ser.getId());
        while (server.getStatus().value().equals("ACTIVE") == false) {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException ex) {
            }
            server = serverApi.get(ser.getId());
        }

        System.out.println(ser.getId());
    }
}

I am getting HttpResponseException but able to get image Id, flavor Id etc.

exception : org.jclouds.http.HttpResponseException: command: POST http://192.168.1.224:8774/v2/e02b6387fa5a4b619bc2ba554661ea99/servers HTTP/1.1 failed with response: HTTP/1.1 400 Bad Request; content: [{"badRequest": {"message": "Multiple possible networks found, use a Network ID to be more specific.", "code": 400}}]

You have to specify the flavor, image and networks to be used to launching an instance. I see you have specified the flavor and image. However, you also have to specify the networks to be used. Check the answer in the below link

jcloud_create_instance_with_network