Since [JDK-8389325](https://bugs.openjdk.org/browse/JDK-8389325) `ObjectMonitor::_metadata` only contains a copy of the object’s hash code. But:
1. A `ObjectMonitorTable` lookup get the hash directly from the object’s mark word, and ... 2. ... no synchronization code uses the copy stored in the monitor. Therefore this PR removes the redundant `_metadata` field and its related metadata/hash accessors, diagnostics, and serviceability support. Passes tier1-5 tests successfully on supported platforms. --------- - [x] I confirm that I make this contribution in accordance with the [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). ------------- Commit messages: - 8390970: Remove ObjectMonitor::_metadata Changes: https://git.openjdk.org/jdk/pull/32573/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=32573&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8390970 Stats: 106 lines in 9 files changed: 12 ins; 71 del; 23 mod Patch: https://git.openjdk.org/jdk/pull/32573.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/32573/head:pull/32573 PR: https://git.openjdk.org/jdk/pull/32573
