RFR: 6968351: httpserver clashes with delayed TCP ACKs for low Content-Length [v5]

[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:

  ignore flush() on closed stream

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18667/files
  - new: https://git.openjdk.org/jdk/pull/18667/files/3cf69db1..d9126b96

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18667&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18667&range=03-04

  Stats: 4 lines in 1 file changed: 3 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