Closes gh-22629

Closes gh-19557

Closes gh-22626

This commit harmonizes dependency declarations for Jackson in the
actuator. Both Jackson and JSR 310 are back to optional in the core
actuator module and mandatory when using the auto-configuration.

Closes gh-22624

Closes gh-22622

Closes gh-22591

Closes gh-22620

* gh-22614:
  Upgrade to Gradle Enterperise Maven Extension 1.6.0

Closes gh-22614

See gh-22614

* gh-22616:
  Add ElasticsearchReactiveHealthIndicator to docs

Closes gh-22616

See gh-22616

Closes gh-22617

* gh-22598:
  Fix link to Elasticsearch health indicator

Closes gh-22598

See gh-22598

Closes gh-22611

* gh-22604:
  Polish "Use milliseconds when configuring awaitTerminationPeriod"
  Use milliseconds when configuring awaitTerminationPeriod

Closes gh-22604

See gh-22604

Prior to this change, TaskExecutorBuilder used seconds as its precision
to map the awaitTerminationPeriod value. This caused a loss of
millisecond information in the period.

This commit fixes the loss by converting the period to millisecond and
using setAwaitTerminationMillis to configure the executor.

See gh-22604

Closes gh-22608

Closes gh-22607

Closes gh-22596

Closes gh-20408

Closes gh-22592

Closes gh-20896

Closes gh-22589

Closes gh-21696

Closes gh-22587

Closes gh-22278

Closes gh-22585

Previously, ignoring invalid fields would cause the failure for an
unknown field to be ignored, irrespective of the ignoreUnknownFields
attribute on `@ConfigurationProperties`.

This commit updates the NoUnboundElementsBindHandler to ensure that
any UnboundConfigurationPropertiesException is thrown rather than
being ignored when the handler has been wrapped by an
IgnoreErrorsBindHandler.

Fixes gh-22308

Closes gh-22583

The fix for gh-20916 updated DefinitionsParser so that the
ResolvableType for each MockBean or SpyBean field included the
implementation class from which the field was found. Where the field
was declared with a variable generic signature that was made constant
by its implementation class, this allowed the correct concrete type to
be determined. It also had the unintended side-effect of preventing two
test classes with identical `@MockBean` and `@SpyBean` configuration
from sharing a context as the resolvable types for their mock and spy
bean fields would now be different.

This commit updates DefinitionsParser to only include the
implementation class in the ResolvableType if the field's generic type
is variable. For cases where it is not variable, this restores the
behaviour prior to the fix for gh-20916.

Fixes gh-22566

Closes gh-22580

Previously, background pre-init was started in response to the
application starting event. This meant that it would be running while
the logging turbo filter was in place and was rejecting all logging.
As a result, any logging performed during pre-init would be lost.

This commit changes background pre-init so that it is now started
in response to the application environment prepared event. By this
point, the logging turbo filter has been removed as the logging levels
have been configured from the environment.

Closes gh-21897

Closes gh-22578