RFR: 6968351: httpserver clashes with delayed TCP ACKs for low Content-Length [v24]

[robert engels]

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

robert engels has updated the pull request incrementally with two additional commits since the last revision:

 - Update src/jdk.httpserver/share/classes/sun/net/httpserver/ChunkedOutputStream.java
   
   Co-authored-by: Daniel Fuchs <67001856+dfuch at users.noreply.github.com>
 - Revert "update copyright date"
   
   This reverts commit 207a3a92022a38843b340f6a021b74f7e9b50fa6.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18667/files
  - new: https://git.openjdk.org/jdk/pull/18667/files/61d3f657..e9ab3a70

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18667&range=23
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18667&range=22-23

  Stats: 6 lines in 5 files changed: 0 ins; 0 del; 6 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