Code to Fix KV discard policy on upgrade to 2.7.2

KvFixDiscardPolicy.java

import io.nats.client.Connection;
import io.nats.client.JetStreamApiException;
import io.nats.client.JetStreamManagement;
import io.nats.client.Nats;
import io.nats.client.api.DiscardPolicy;
import io.nats.client.api.StreamConfiguration;
import io.nats.client.api.StreamInfo;
import io.nats.client.support.NatsKeyValueUtil;

import java.util.List;

public class KvFixDiscardPolicy {

    // USAGE NOTES:
    // 1. Use whatever connect(...) call you need, for instance if you need user/pass
    // This would apply while connecting to the server on line 28
    //     public static Connection connect(Options options) throws IOException, InterruptedException {
    //     public static Connection connect(String url) throws IOException, InterruptedException {
    //     public static Connection connect(String url, AuthHandler handler) throws IOException, InterruptedException {
    //     public static Connection connect(Options options) throws IOException, InterruptedException {
    //
    // 2. You may need to use JetStreamOptions when creating your management context, for accounts/prefixes/domains
    // This would apply to getting the JetStreamManagement context on line 31.
    //     JetStreamManagement jetStreamManagement() throws IOException;
    //     JetStreamManagement jetStreamManagement(JetStreamOptions options) throws IOException;

    public static void main(String[] args) {

        try (Connection nc = Nats.connect()) {
            // get a JetStreamManagement context
            JetStreamManagement jsm = nc.jetStreamManagement();

            // get a list of all the stream names and then loop through them all
            List<String> streamNames = jsm.getStreamNames();
            for (String streamName : streamNames) {

                // bucket stream names start with 'KV_'
                if (streamName.startsWith("KV_")) {
                    String bucket = NatsKeyValueUtil.extractBucketName(streamName);
                    System.out.print("Updating Bucket `" + bucket + "` -> ");

                    try {
                        // lookup the stream info which contains the stream config
                        StreamInfo si = jsm.getStreamInfo(streamName);

                        // if the policy is already correct, nothing to do
                        if (si.getConfiguration().getDiscardPolicy() == DiscardPolicy.New) {
                            System.out.println("Already Updated.");
                        }
                        else {
                            // build a new stream configuration with the old configuration
                            // plus the changed discard policy.
                            StreamConfiguration sc = StreamConfiguration.builder(si.getConfiguration())
                                .discardPolicy(DiscardPolicy.New)
                                .build();

                            // update the stream
                            si = jsm.updateStream(sc);

                            // double check that the update worked
                            if (si.getConfiguration().getDiscardPolicy() == DiscardPolicy.New) {
                                System.out.println("Update Successful");
                            }
                            else {
                                System.out.println("Update Failed Without Exception");
                            }
                        }
                    } catch (JetStreamApiException jsae) {
                        System.out.println("Update Failed With Exception: ");
                        jsae.printStackTrace();
                    }
                }
                else {
                    System.out.println("Skipping Non-Kv Stream `" + streamName + "`.");
                }
            }
        }
        catch (Exception e) {
            System.out.println("Program Failed With Exception.");
            e.printStackTrace();
        }
    }
}