Closes gh-15901
Closes gh-15638

Closes gh-15862

Closes gh-15878

See gh-15775

Closes gh-15890

Closes gh-15348

When Spring Security is misconfigured it's possible to switch from an anonymous user
to a normal user. When switching back again, the corresponding
AuthenticationSwitchUserEvent will have a null target user. Previously, Actuator's
AuthenticationAuditListener would throw a NullPointerException when it received such an
event.

This commit updates the audit listener to defensively handled events with a null target
user.

Closes gh-15767

* pr/15859:
  Polish contribution
  Polish 'Database Initialization' section

Closes gh-15859

See gh-15859

* gh-15775:
  Polish "Use class for @ConditionalOnClass"
  Use class for @ConditionalOnClass

Closes gh-15775

See gh-15775

See gh-15775

This reverts commit 1f47bd97.

See gh-15915

Previously, the auto-configuration for both Jersey and WebMvc would auto-configure
a RequestContextFilter bean. In 2.1.0, this led to a startup failure due to the latter
attempting to override the bean defined by the former. In addition to the override there
were also problems with the order of the filter as Jersey uses -1 and MVC uses -105.

To avoid the above-described problems, the auto-configuration of the RequestContextFilter
was removed from JerseyAutoConfiguration in 2.1.1. Unfortunately, the broke
request-scoped beans for those using only Jersey.

This commit attempts to strike a better balance by reintroducing the auto-configuration
of RequestContextFilter in JerseyAutoConfiguration. It will back off if the user defines
their own filter or filter registration. WebMvcAutoConfiguration has been updated to
back off in the same manner. This leaves the potential for ordering problems, but they
are no worse than they were before. Furthermore, the user has the means to correct any
problems by using the various filter ordering properties that are provided for Jersey,
Spring Session, Spring Security, etc.

Closes gh-15376

This reverts commit 06feb728.

See gh-15914

* pr/15881:
  Polish "Document internationalization support"
  Document internationalization support

Closes gh-15881

See gh-15881

Closes gh-15928

Closes gh-15927

Closes gh-15926

Closes gh-15925

Closes gh-15924

Closes gh-15923

Closes gh-15922

Closes gh-15921

Closes gh-15920

Closes gh-15919

Closes gh-15918

Closes gh-15917

Closes gh-15916

Closes gh-15915

Closes gh-15914

Closes gh-15913

Closes gh-15912

Closes gh-15911

Closes gh-15910

Closes gh-15909