[jdk13u-dev] RFR: 8277422: tools/jar/JarEntryTime.java fails with modified time mismatch

[Yuri Nesterenko]

Clean backport of test-only fix.

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Commit messages:
 - Backport ad1ff27b730773a141d73744e5f5a899bdfbea78

Changes: https://git.openjdk.org/jdk13u-dev/pull/375/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk13u-dev&pr=375&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8277422
  Stats: 11 lines in 1 file changed: 9 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk13u-dev/pull/375.diff
  Fetch: git fetch https://git.openjdk.org/jdk13u-dev pull/375/head:pull/375

PR: https://git.openjdk.org/jdk13u-dev/pull/375