Summary
-------

Update the thread dump generated by `com.sun.management.HotSpotDiagnosticMXBean.dumpThreads` and the `jcmd <pid> Thread.dump_to_file` diagnostic command to include thread state and lock information.

Update `com.sun.management.HotSpotDiagnosticMXBean.dumpThreads` to describe the structure of the JSON thread dump.


Problem
-------

The thread dump generated by `HotSpotDiagnosticMXBean.dumpThreads` and `jcmd <pid> Thread.dump_to_file` doesn't include lock information that is important for troubleshooting.

The JSON format thread dump is intended to be read by tools but the structure is not documented.


Solution
--------

Update the thread dump, both plain text format and JSON format, to include the following:

- the thread state
- the "parkBlocker" when a thread is parked
- the object that the thread is blocked on when blocked on monitor enter
- the locks (object monitors) that were acquired in each frame
- where possible, the object that a thread is waiting on when waiting in `Object.wait`.

Specification
-------------

`HotSpotDiagnosticMXBean.dumpThreads` is updated to link to a JSON object that describes the thread dump format. The linked file (threadDump.schema.json) is attached.

```
@@ -116,6 +116,13 @@ public interface HotSpotDiagnosticMXBean extends PlatformManagedObject {
      * {@code outputFile} parameter must be an absolute path to a file that
      * does not exist.
      *
+     * <p> When the format is specified as {@link ThreadDumpFormat#JSON JSON}, the
+     * thread dump is generated in JavaScript Object Notation.
+     * <a href="doc-files/threadDump.schema.json">threadDump.schema.json</a>
+     * describes the thread dump format in draft
+     * <a href="https://tools.ietf.org/html/draft-json-schema-language-02">
+     * JSON Schema Language version 2</a>.
+     *
      * <p> The thread dump will include output for all platform threads. It may
      * include output for some or all virtual threads.
      *
@@ -151,6 +158,7 @@ public static enum ThreadDumpFormat {
         TEXT_PLAIN,
         /**
          * JSON (JavaScript Object Notation) format.
+         * @spec https://datatracker.ietf.org/doc/html/rfc8259 JavaScript Object Notation
          */
         JSON,
     }
```

There are no updates needed to the `jcmd` man page.