[jdk21u-dev] RFR: 8320577: Improve MessageHeader's toString() function to make HttpURLConnection's debug log readable

[Daniel Hu]

Improves HttpURLConnection debug logs. GHA passes.

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Commit messages:
 - Merge branch 'openjdk:master' into 8320577
 - Backport aac43184319d852eb792c83dfb52d74a3126108d

Changes: https://git.openjdk.org/jdk21u-dev/pull/2252/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2252&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8320577
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2252.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2252/head:pull/2252

PR: https://git.openjdk.org/jdk21u-dev/pull/2252