[jdk17u-dev] RFR: 8304927: Update java/net/httpclient/BasicAuthTest.java to check basic auth over HTTP/2

[Goetz Lindenmaier]

I backport this for parity with 17.0.12-oracle.

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Commit messages:
 - Backport 50a995f03a0cc5c342929a0f48c43fd04fdf0b0d

Changes: https://git.openjdk.org/jdk17u-dev/pull/2386/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2386&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8304927
  Stats: 411 lines in 3 files changed: 220 ins; 145 del; 46 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2386.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2386/head:pull/2386

PR: https://git.openjdk.org/jdk17u-dev/pull/2386