RFR: Merge jdk

[Mikael Vidstedt]

Merge in jdk-15+19

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Commit messages:
 - Merge jdk
 - 8242366: Fix JavaDoc warnings
 - 8242842: Avoid reallocating name when checking for trailing slash in ZipFile.getEntryPos
 - 8242629: Remove references to deprecated java.util.Observer and Observable
 - 8242597: Remove GenericTaskQueue<>::push_slow
 - 8241618: Fix trivial unchecked warnings for jdk.hotspot.agent
 - 8242485: Null _file checking in fileStream::flush()
 - 8242643: Shenandoah: split concurrent weak and strong root processing
 - 8242602: Shenandoah: allow earlier recycle of trashed regions during concurrent root processing
 - Merge
 - ... and 494 more: https://git.openjdk.java.net/portola/compare/8973e522...5319482e

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - master: https://webrevs.openjdk.java.net/portola/3/webrev.00.0
 - jdk: https://webrevs.openjdk.java.net/portola/3/webrev.00.1

Changes: https://git.openjdk.java.net/portola/pull/3/files
  Stats: 952954 lines in 2885 files changed: 774183 ins; 164217 del; 14554 mod
  Patch: https://git.openjdk.java.net/portola/pull/3.diff
  Fetch: git fetch https://git.openjdk.java.net/portola pull/3/head:pull/3

PR: https://git.openjdk.java.net/portola/pull/3