[jdk11u-dev] RFR: 8266460: java.io tests fail on null stream with upgraded jtreg/TestNG

[George Adams]

Backport required to bump JDK11u to jtreg 6

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Commit messages:
 - Backport e8405970b9998ff8f77bcf196f1456713a98c47f

Changes: https://git.openjdk.org/jdk11u-dev/pull/1254/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1254&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8266460
  Stats: 119 lines in 4 files changed: 12 ins; 24 del; 83 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1254.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1254/head:pull/1254

PR: https://git.openjdk.org/jdk11u-dev/pull/1254