Fixing the race condition during the initialization of the skeleton map. The root cause was that the map could be accessed while it was still being initialized, leading to an NPE. Although the NPE could be avoided by returning a default value, the map initialization itself should be made thread safe.
--------- - [x] I confirm that I make this contribution in accordance with the [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). ------------- Commit messages: - initial commit Changes: https://git.openjdk.org/jdk/pull/31006/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=31006&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8383525 Stats: 112 lines in 2 files changed: 83 ins; 7 del; 22 mod Patch: https://git.openjdk.org/jdk/pull/31006.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/31006/head:pull/31006 PR: https://git.openjdk.org/jdk/pull/31006
