Closes gh-21918

Closes gh-21910

Closes gh-21917

Closes gh-21916

* pr/21906:
  Update copyright year of changed files
  Fix wrong property reference to keys-to-sanitize in Javadoc

Closes gh-21906

See gh-21906

See gh-21906

Closes gh-21915

Closes gh-21908

Closes gh-21904

Update `AvailabilityChangeEvent` to be a `PayloadEvent` and ensure
that the `getResolvableType` method returns a generic compatible
result.

Prior to this commit, a ClassCastExeption would be thrown if the
following event listener was declared:

  @EventListener
  void onEvent(AvailabilityChangeEvent<ReadinessState> event) {
    ...
  }

Closes gh-21898

Cherry-pick release script updates from 2.3.x

See gh-21474

Closes gh-21900

See gh-21474

Improve logging and fix a few issue with the release script.

See gh-21474

Update the release tooling to check for bintray published artifacts
using SHA256 digests and to also check before attempting a promote.

See gh-21474

Closes gh-21896

Reinstate test now that we are on a reactor-netty releases that fixes
reactor/reactor-netty issue 1093.

Closes gh-21437

Further attempt to fix Windows file issues.

See gh-21575

Closes gh-21895

Update `BuildRequest` to also allow digest based references.

Closes gh-21879

Refactor the internals of `PropertiesLauncher` so that opened jar files
are tracked and can be closed after a test completes.

See gh-21575

Update Ant smoke test to explicitly use Java 8.

Closes gh-21894

* pr/21872:
  Fix deprecation in NettyRSocketServerFactoryTests

Closes gh-21872

See gh-21872

Closes gh-21893

* pr/21793:
  Link complete Slack message to build log

Closes gh-21793

See gh-21793

Closes gh-21892

This commit changes the NamedPipeSocket used for communication with
a local Docker daemon to use a non-blocking AsynchronousByteChannel
instead of a blocking RandomAccessFile, modeled after a similar
change to the docker-java project. This eliminates the potential for
a blocking call to hang indefinitely.

Fixes gh-21672

Closes gh-21891