RFR: 6968351: httpserver clashes with delayed TCP ACKs for low Content-Length [v21]

[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:

  add https testing

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/18667/files
  - new: https://git.openjdk.org/jdk/pull/18667/files/e31f4879..f9bc4e4d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18667&range=20
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18667&range=19-20

  Stats: 39 lines in 1 file changed: 22 ins; 3 del; 14 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