[lworld] RFR: 8320437: [lworld] Adding internal null-restricted storage API points

[Frederic Parain]

Adding internal null-restricted storage API points

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Commit messages:
 - Remove empty line
 - More tests migrated
 - Fix test
 - Test code cleanup
 - Fix javadoc
 - Merge remote-tracking branch 'upstream/lworld' into annotations
 - Add support for atomicity plus various fixes
 - Adding internal null-restricted storage API points

Changes: https://git.openjdk.org/valhalla/pull/947/files
 Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=947&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8320437
  Stats: 1140 lines in 26 files changed: 1023 ins; 17 del; 100 mod
  Patch: https://git.openjdk.org/valhalla/pull/947.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/947/head:pull/947

PR: https://git.openjdk.org/valhalla/pull/947