[jdk8u-dev] RFR: 8285836: sun/net/www/http/KeepAliveCache/KeepAliveProperty.java failed with "RuntimeException: Failed in server"

[Stewart X Addison]

Backport of https://github.com/openjdk/jdk11u-dev/pull/1377
Eclipse Temurin has seen this failure on some systems and this backport resolves them.

Sample failure when trying 100 iterations: https://ci.adoptium.net/job/Grinder/15544/testReport/ (82/100 failed)
Sample pass with this branch: https://ci.adoptium.net/job/Grinder/15551/testReport (zero failures)

Ref: https://bugs.openjdk.org/browse/JDK-8285836

Testing tier 1:
- [Linux/x64](https://ci.adoptium.net/job/Grinder/15559/testReport)
- [Linux/aarch64](https://ci.adoptium.net/job/Grinder/15558/testReport)
- [Windows/x64](https://ci.adoptium.net/job/Grinder/15563/testReport)
- [Mac/x64](https://ci.adoptium.net/job/Grinder/15565/testReport)
- [AIX](https://ci.adoptium.net/job/Grinder/15564/testReport)

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Commit messages:
 - Backport af529be069b651808310c3c37e2167d216979f69

Changes: https://git.openjdk.org/jdk8u-dev/pull/721/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=721&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8285836
  Stats: 3 lines in 1 file changed: 2 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/721.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev.git pull/721/head:pull/721

PR: https://git.openjdk.org/jdk8u-dev/pull/721