Closes gh-1885

See gh-1885

Issue: SPR-17040

Closes gh-23994

Closes gh-23996

This commit adds support for Continuation parameter that is now
considered as an optional parameter since it is never provided by
the user.

It also simplifies and optimizes the implementation.

Closes gh-23991

* pr/23995:
  Polish CorsAbstractHandlerMappingTests

Closes gh-23995

See gh-23995

See gh-23895

See gh-23895

Prior to this commit, InstantFormatter was able to properly serialize
an Instant that is far in the future (or in the past), but it could not
properly deserialize it, because in such scenarios an ISO-formatted
Instant starts with a +/- sign.

This commit fixes this issue, while maintaining the previous contract,
and also introduces tests for InstantFormatter.

Closes gh-23895

Closes gh-22451

Closes gh-23761

Closes gh-23934

...or skip if there are no values either.

Closes gh-22372

Closes gh-1956

See gh-1956

Closes gh-23984

* https://github.com/spring-projects/spring-framework/blob/3a0f309e2c9fdbbf7fb2d348be861528177f8555/spring-web/src/main/java/org/springframework/http/codec/ServerSentEvent.java#L24
* https://github.com/spring-projects/spring-framework/blob/3a0f309e2c9fdbbf7fb2d348be861528177f8555/spring-web/src/main/java/org/springframework/http/codec/ClientCodecConfigurer.java#L88
* https://github.com/spring-projects/spring-framework/blob/ef14d76d3637abeb31edd8a22031c21f9445efef/spring-web/src/main/java/org/springframework/http/codec/ServerCodecConfigurer.java#L94
* https://github.com/spring-projects/spring-framework/blob/3a0f309e2c9fdbbf7fb2d348be861528177f8555/spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/handler/EventSourceTransportHandler.java#L33

Prior to this commit, the schemaZip Gradle task failed to find Spring
schema files on MS Windows due to path separators hard coded to forward
slashes that are not compatible with the Windows operating system.

Consequently, a full build failed on Windows since the distZip task was
not able to locate the zipped schema archive that the schemaZip task
failed to create.

This commit fixes this by updating the schemaZip task to search for
schema files using backslashes as well as forward slashes.

Closes gh-23933

Closes gh-23812

Closes gh-23977

Closes gh-23978

Closes gh-23980

See gh-23296

See gh-23296

Closes gh-23929

See gh-23784