[jdk11u-dev] RFR: 8213189: Make restricted headers in HTTP Client configurable and remove Date by default

[Christoph Langer]

Backport of JDK-8213189: Make restricted headers in HTTP Client configurable and remove Date by default.

I had to fit the patch a bit into the context of 11u, but no modifications necessary.

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Commit messages:
 - Backport 028f2e14b3550dd1f2a358a2a0aaf83d4a824af0

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/355/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=355&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8213189
  Stats: 383 lines in 14 files changed: 355 ins; 7 del; 21 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/355.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/355/head:pull/355

PR: https://git.openjdk.java.net/jdk11u-dev/pull/355