If the lag detector's logger is set to `DEBUG` then the master will capture the hot threads on the lagging node and report them in its logs. However it's quite possible for this log message to be many kB in size, and log messages are apparently truncated at 10kB by default.

We should find another way to report this information to avoid hitting this size limit. Perhaps simply split the hot threads output up across multiple log messages, or perhaps find a different way to report it.
server/src/main/java/org/elasticsearch/common/ReferenceDocs.java
/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */
package org.elasticsearch.common;
import org.elasticsearch.Build;
import org.elasticsearch.Version;
import java.util.Arrays;
import java.util.List;
/**
 * Encapsulates links to pages in the reference docs, so that for example we can include URLs in logs and API outputs. Each instance's
 * {@link #toString()} yields (a string representation of) a URL for the relevant docs.
 */
public enum ReferenceDocs {
    INITIAL_MASTER_NODES("important-settings.html#initial_master_nodes"),
    DISCOVERY_TROUBLESHOOTING("discovery-troubleshooting.html"),
    UNSTABLE_CLUSTER_TROUBLESHOOTING("cluster-fault-detection.html#cluster-fault-detection-troubleshooting");
    private final String relativePath;
    ReferenceDocs(String relativePath) {
        this.relativePath = relativePath;
    }
    static final String UNRELEASED_VERSION_COMPONENT = "master";
    static final String VERSION_COMPONENT = getVersionComponent(Version.CURRENT, Build.CURRENT.isSnapshot());
    /**
     * Compute the version component of the URL path (e.g. {@code 8.5} or {@code master}) for a particular version of Elasticsearch. Exposed