[jdk21u] RFR: 8301457: Code in SendPortZero.java is uncommented even after JDK-8236852 was fixed

[Goetz Lindenmaier]

I backport this for parity with 17.0.11-oracle. 21u should not fall back.

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Commit messages:
 - Backport 298dda4c985ddda84e264aff86ea45c849bb171c

Changes: https://git.openjdk.org/jdk21u/pull/307/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=307&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8301457
  Stats: 37 lines in 2 files changed: 14 ins; 14 del; 9 mod
  Patch: https://git.openjdk.org/jdk21u/pull/307.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/307/head:pull/307

PR: https://git.openjdk.org/jdk21u/pull/307