Alter the logic of `MustacheEnvironmentCollector` so that the
native fetcher is always consulted if it exists.

When the context is a map (as it is in a web View for instance) you
can't assume a non-null fetcher actually contains the property you are
searching for.

See gh-21060

* pr/21650:
  Polish 'Clarify documentation for probe ports'
  Clarify documentation for probe ports

Closes gh-21650

See gh-21650

Update the reference documentation to provide a better description of
the port that should be used for Kubernetes probes.

See gh-21650

* pr/21758:
  Use supplier assertions in availability indicator

Closes gh-21758

See gh-21758

Closes gh-21762

* gh-20716:
  Polish "Clarify loss of defaults when adding custom mapping"
  Clarify loss of defaults when adding custom mapping

Closes gh-20716

See gh-20716

See gh-20716

Closes gh-21760

Closes gh-21759

Closes gh-19293

Closes gh-21755

Closes gh-21754

Previously, the spring bash script added . to the classpath but the
Windows spring.bat script did not. This commit aligns the classpath
of the two scripts by removing . from the classpath in the bash
script.

Fixes gh-19910

Closes gh-21752

Closes gh-21751

Closes gh-15358

* pr/21381:
  Polish 'Support userInfo in elasticsearch URI'
  Support userInfo in elasticsearch URI

Closes gh-21381

See gh-21381

See gh-21381

Closes gh-21744

Closes gh-21743

Closes gh-21737

See gh-21739

See gh-21738

See gh-21729

* pr/20929:
  Polish 'Allow beans without public constructors to load'
  Allow beans without public constructors to load

Closes gh-20929

See gh-20929

Allow `BeanDefinitionLoader` to load classes that don't have public
constructors. The constraint was first introduced in d82c5080 to
solve an issue with anonymous Groovy classes but causes particular
problems with `@SpringBootTest`.

See gh-20929

* pr/21732:
  Polish

Closes gh-21732