JDK 15 introduces isEmpty() on CharSequence which clashes with the one
declared in StringSequence because it is not public.

See gh-21713

In JDK 15 the concept of hidden classes was introduced, which also
affects Lambdas in so far that Class.getCanonicalName() will return null
for those. This commit uses Class.getName() as a fallback when no
canonical name is available.

See gh-21713

* pr/21533:
  Polish "Add support for webAdminPassword property of H2 Console"
  Add support for webAdminPassword property of H2 Console

Closes gh-21533

See gh-21533

See gh-21533

* pr/20887:
  Polish "Add health indicator for Cassandra that uses the CqlSession"
  Add health indicator for Cassandra that uses the CqlSession

Closes gh-20887

See gh-20887

This commit provides a CassandraDriverHealthIndicator and
CassandraDriverReactiveHealthIndicator that do not require Spring Data.
As a result, a health indicator for Cassandra is provided even if the
application does not use Spring Data.

See gh-20887

* gh-21912:
  Polish "Fix detection of snapshot version when configuring repositories"
  Fix detection of snapshot version when configuring repositories

Closes gh-21912

See gh-21912

As part of 8e854875, snapshot dependency resolution change from
`BUILD-SNAPSHOT` to `-SNAPSHOT`. Currently, if we add a version
dependency which is store in snapshots it is not resolved. This
commit allow to resolves plugins and dependencies.

See gh-21912

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