[jdk17u-dev] RFR: 8297200: java/net/httpclient/SpecialHeadersTest.java failed once in AssertionError due to selector thread remaining alive

[Goetz Lindenmaier]

I backport this for parity with 17.0.17-oracle.

Resolved @bug tag in the test file, probably clean anyways.

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Commit messages:
 - Backport d83a07b72cfd4dc42c5d4815262fcba05c653bd5

Changes: https://git.openjdk.org/jdk17u-dev/pull/3673/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=3673&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8297200
  Stats: 103 lines in 4 files changed: 79 ins; 0 del; 24 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/3673.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/3673/head:pull/3673

PR: https://git.openjdk.org/jdk17u-dev/pull/3673