I developing some ui tools for kafka. If bootstrap servers are avaialable there is not problem.
But if any bootstrap server is not available i have to handle this.

Also i read this org.apache.kafka.adminclient codes on the github and i saw networkclient has a attribute for this connection status for every node.Networkclient is trying connect to nodes for multiple times. If i can read that connection status, everything gonna wil work as expected.

I can get the status of nodes with below codes but nodes().get() has a timeout and its not best practice for this situation.

 @Override
public boolean checkClusterStatus(Cluster cluster, int unit, TimeUnit unitType) throws Exception {
    DescribeClusterResult clusterResult = cluster.getAdminClient().describeCluster();
    AdminClient client = cluster.getAdminClient();
    try {
        Collection<Node> nodes = clusterResult.nodes().get(unit,unitType);
        //if there is any node details, cluster is available

        System.out.println("Cluster is available with nodes - " + nodes);
    } catch (InterruptedException | ExecutionException | TimeoutException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        cluster.setClusterStatusAvailable(false);
        return false;
    }  
    
    cluster.setClusterStatusAvailable(true);
    return true;
}