RFR: Fixing nullability regression tests

[Vicente Romero]

fixing nullability regression tests

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Commit messages:
 - Merge branch 'bworld' into fixing.regression.tests.in.bworld
 - fixing nullability regression tests
 - fixing regression tests in bworld

Changes: https://git.openjdk.org/valhalla/pull/1849/files
  Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=1849&range=00
  Stats: 747 lines in 10 files changed: 3 ins; 711 del; 33 mod
  Patch: https://git.openjdk.org/valhalla/pull/1849.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/1849/head:pull/1849

PR: https://git.openjdk.org/valhalla/pull/1849