See gh-20953

See gh-20951

See gh-20949

See gh-20947

See gh-20945

See gh-20943

Closes gh-20968

Closes gh-20964

Closes gh-20963

Closes gh-20623

Closes gh-20962

Update the application availability and probes documentation following
the recent set of updates.

See gh-20962

Update the `HealthEndpointGroups` customization support to use a
post-processor rather than a mutable registry. Although this approach
is slightly less flexible, it removes a lot of complexity from the
`HealthEndpointGroups` code. Specifically, it allows us to drop the
`HealthEndpointGroupsRegistry` interface entirely.

The probe health groups are now added via the post-processor if they
aren't already defined. Unlike the previous implementation, users are
no longer able to customize status aggregation and http status code
mapping rules _unless_ they also re-define the health indicators that
are members of the group.

See gh-20962

Update `AvailabilityProbesAutoConfiguration` to allow the
`management.health.probes.enabled` property to override the platform
detection logic. Prior to this commit, it was possible to use the
property to enable the probes, but it was not possible to disable
them when deploying to Kubernates.

See gh-20962

Relocate probe auto-configuration from the `kubernetes` package to
`availability` since probes could also be used on other platforms.

The classes have also been renamed to named to `AvailabilityProbes...`

See gh-20962

Rename `LivenessProbeHealthIndicator` to `LivenessStateHealthIndicator`
and `ReadinessProbeHealthIndicator` to `ReadinessStateHealthIndicator`.

Also introduce a general purpose `AvailabilityStateHealthIndicator`
class.

See gh-20962

Create a general purpose `AvailabilityState` interface and refactor
the existing `LivenessState` and `ReadinessState` to use it. A single
`AvailabilityChangeEvent` is now used to carry all availability state
updates.

This commit also renames `ApplicationAvailabilityProvider` to
`ApplicationAvailabilityBean` and extracts an `ApplicationAvailability`
interface that other beans can inject. The helps to hide the event
listener method, which is really internal.

Finally the state enums have been renamed as follows:

 - `LivenessState.LIVE` -> `LivenessState.CORRECT`
 - `ReadinessState.READY` -> `ReadinessState.ACCEPTING_TRAFFIC`
 - `ReadinessState.UNREADY` -> `ReadinessState.REFUSING_TRAFFIC`

See gh-20962

Closes gh-20958

See gh-20952

See gh-20950

See gh-20948

See gh-20946

See gh-20944

See gh-20942

Closes gh-20957

Prior to this commit, the Undertow compression configuration provided by
Spring Boot would fail and throw an exception for invalid MIME Types
when trying to check them against the list of configured types for
compression.

This commit ensures that invalid MIME Types are ignored and that
compression is disabled for those.

Fixes gh-20955

See gh-20941

See gh-20940

See gh-20939

See gh-20938

See gh-20937

* pr/20931:
  Polish

Closes gh-20931

See gh-20931

* pr/20872:
  Change PropertiesLauncher equals method to use URI

Closes gh-20872

See gh-20872