RFR: 8287593: ShortResponseBody could be made more resilient to rogue connections [v3]

[Ryan Ernst]

> Since ReplyingServer binds to an open port on the system where tests
> run, it is possible some other program probes that port while the test
> is running. If the probe request does not have request params, the
> request is invalid and a test assertion fails. This commit replaces that
> assertion with returning a 400 response.

Ryan Ernst has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - Merge branch 'master' into httpclient_test_assert
 - better log message
 - Merge branch 'master' into httpclient_test_assert
 - 8287593: ShortResponseBody could be made more resilient to rogue connections
   
   Since ReplyingServer binds to an open port on the system where tests
   run, it is possible some other program probes that port while the test
   is running. If the probe request does not have request params, the
   request is invalid and a test assertion fails. This commit replaces that
   assertion with returning a 400 response.

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9329/files
  - new: https://git.openjdk.org/jdk/pull/9329/files/46125a78..8e91bd44

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9329&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9329&range=01-02

  Stats: 1157 lines in 27 files changed: 1066 ins; 18 del; 73 mod
  Patch: https://git.openjdk.org/jdk/pull/9329.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9329/head:pull/9329

PR: https://git.openjdk.org/jdk/pull/9329