RFR: 6968351: httpserver clashes with delayed TCP ACKs for low Content-Length [v11]

[robert engels]

> fix bug JDK-B6968351 by avoiding flush after response headers

robert engels has updated the pull request incrementally with one additional commit since the last revision:

  rename testcase for clarity

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18667/files
  - new: https://git.openjdk.org/jdk/pull/18667/files/1e278f23..c94f3c2b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18667&range=10
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18667&range=09-10

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/18667.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18667/head:pull/18667

PR: https://git.openjdk.org/jdk/pull/18667