[jdk21u-dev] RFR: 8306040: HttpResponseInputStream.available() returns 1 on empty stream

[Goetz Lindenmaier]

I backport this for parity with 21.0.4-oracle.

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Commit messages:
 - Backport acaab6fd74f507bb6b18167505d88e505bdf24bd

Changes: https://git.openjdk.org/jdk21u-dev/pull/309/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=309&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306040
  Stats: 163 lines in 2 files changed: 161 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/309.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/309/head:pull/309

PR: https://git.openjdk.org/jdk21u-dev/pull/309