Migrates `test/jdk/java/net/httpclient/` to null-safe `SimpleSSLContext` methods introduced in [JDK-8372661], which is a prerequisite for this change set.
[JDK-8372661]: https://bugs.openjdk.org/browse/JDK-8372661 ------------- Commit messages: - Restore `test/jdk/java/net/httpclient/` changes - Reverted all changes and only kept `SimpleSSLContext` enhancements - Overhaul `SimpleSSLContext` and its usages Changes: https://git.openjdk.org/jdk/pull/28771/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28771&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8373515 Stats: 1073 lines in 180 files changed: 108 ins; 667 del; 298 mod Patch: https://git.openjdk.org/jdk/pull/28771.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/28771/head:pull/28771 PR: https://git.openjdk.org/jdk/pull/28771
