What happens when we add new buckets to a Prometheus Histogram dynamically?

TempPrometheusVaryingHistogram.java

package io.micrometer.core.samples;

import com.sun.net.httpserver.HttpServer;

import java.io.IOException;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.util.Map;
import java.util.TreeMap;
import java.util.concurrent.atomic.DoubleAdder;
import java.util.stream.Collectors;

public class TempPrometheusVaryingHistogram {
    DoubleAdder count = new DoubleAdder();
    DoubleAdder sum = new DoubleAdder();
    TreeMap<Double, DoubleAdder> buckets = new TreeMap<>();

    DoubleAdder currentValue = new DoubleAdder();

    public static void main(String[] args) {
        new TempPrometheusVaryingHistogram().run();
    }

    public void record(double value) {
        count.add(1);
        sum.add(value);
        buckets.tailMap(value).forEach((bucket, bucketCount) -> bucketCount.add(1));
    }

    public String scrape() {
        return "# HELP summary  \n" +
            "# TYPE summary histogram\n" +
            "summary_count " + count.sum() + "\n" +
            "summary_sum" + sum.sum() + "\n" +
            buckets.entrySet().stream()
                .map(entry -> "summary_bucket{le=\"" + entry.getKey() + "\",} " + entry.getValue())
                .collect(Collectors.joining("\n")) + "\n\n" +

            // so we have a sense of where the current value used for recording is
            "# HELP curValue  \n" +
            "# TYPE curValue gauge\n" +
            "curValue " + currentValue.sum() + "\n";
    }

    // add a new bucket, initializing it's value to be equal to that of the bucket that immediately precedes it
    public void addBucket(double bucket) {
        DoubleAdder initialValue = new DoubleAdder();
        Map.Entry<Double, DoubleAdder> floor = buckets.floorEntry(bucket);
        if(floor != null)
            initialValue.add(floor.getValue().sum());
        buckets.put(bucket, initialValue);
    }

    @SuppressWarnings("Duplicates")
    public void run() {
        addBucket(1);
        addBucket(2);
        addBucket(3);

        currentValue.add(2.5);

        try {
            HttpServer server = HttpServer.create(new InetSocketAddress(8080), 0);
            server.createContext("/prometheus", httpExchange -> {
                record(currentValue.sum());
                currentValue.add(0.1);

                // as we sample higher and higher values, we keep adding buckets
                if(currentValue.sum() > buckets.lastEntry().getKey()) {
                    addBucket(buckets.lastEntry().getKey() + 1);
                }

                String scrape = scrape();
                httpExchange.sendResponseHeaders(200, scrape.length());
                OutputStream os = httpExchange.getResponseBody();
                os.write(scrape.getBytes());
                os.close();
            });

            new Thread(server::start).run();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}