See gh-15809

Closes gh-15870

Closes gh-15197

See gh-16167

This commit adds the newly introduced `@ConditionalOnExposedEndpoint`
conditional annotation to all auto-configured `Endpoint` in Actuator.

With that change, `EndPoint` instances and related infrastructure will
only be created when they are meant to be exposed and used. This will
save CPU and memory resources when Actuator is present.

Closes gh-16093

Prior to this commit, Actuator `Endpoint` instantiations would be
guarded by `@ConditionalOnEnabledEnpoint` condition annotations. This
feature saves resources as disabled endpoints aren't unnecessarily
instantiated.

By default, only `"health"` and `"info"` endpoints are exposed over the
web and all endpoints are exposed over JMX.

As of gh-16090, JMX is now disabled by default. This is an opportunity
to avoid instantiating endpoints if they won't be exposed at all, which
is more likely due to the exposure defaults.

This commit adds a new `@ConditionalOnExposedEndpoint` conditional
annotation that checks the `Environment` for configuration properties
under `"management.endpoints.web.exposure.*"` and
`"management.endpoints.jmx.exposure.*"`. In the case of JMX, an
additional check is perfomed, checking that JMX is enabled first.
The rules implemented in the condition itself are following the ones
described in `ExposeExcludePropertyEndpointFilter`.

See gh-16093

Closes gh-16163

Closes gh-16162

Closes gh-16160

Closes gh-16159

AssertJ includes a change in 3.12 that means that, by default, it now incorrectly
identifies some of the builder methods on CacheControl as accessor methods for its fields.
This commit restores the behaviour of 3.11 so that a method is only considered to be a
property accessor if a matches the Java bean naming conventions.

Closes gh-16145

This reverts commit 53e7c5cd.

See gh-16118

Closes gh-16145

Closes gh-15940

Closes gh-15939

Closes gh-16157

Closes gh-16156

Closes gh-16155

Closes gh-16154

Closes gh-16153

Closes gh-16152

Closes gh-16151

Closes gh-16150

Closes gh-16149

Closes gh-16148