[jdk11u-dev] RFR: 8255227: java/net/httpclient/FlowAdapterPublisherTest.java intermittently failing with TestServer: start exception: java.io.IOException: Invalid preface

[Goetz Lindenmaier]

I downport this for parity with 11.0.13-oracle.

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Commit messages:
 - Backport 0544a732a44309bf7cbb44846dd9320c6096de17

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/430/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=430&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255227
  Stats: 11 lines in 2 files changed: 6 ins; 1 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/430.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/430/head:pull/430

PR: https://git.openjdk.java.net/jdk11u-dev/pull/430