[jdk21u-dev] RFR: 7036144: GZIPInputStream readTrailer uses faulty available() test for end-of-stream

[William Kemper]

Clean backport.

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Commit messages:
 - Backport d3f3011d56267360d65841da3550eca79cf1575b

Changes: https://git.openjdk.org/jdk21u-dev/pull/871/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=871&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-7036144
  Stats: 111 lines in 2 files changed: 96 ins; 9 del; 6 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/871.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/871/head:pull/871

PR: https://git.openjdk.org/jdk21u-dev/pull/871