Fix reference code sample
Fix outdated references to JobDetailBean

Issue: SPR-12306
TextMessage.toString() does not throw StringIndexOutOfBoundsException for payload with multibyte characters

Issue: SPR-12307
WebSocketSession extends java.io.Closeable, plus reorganization of AbstractSockJsSession's code

Issue: SPR-12311
Explicitly detect (and prevent) private @Scheduled methods on CGLIB proxies

Issue: SPR-12308
Consistent use of LinkedHashSet for interfaces (since interface order may matter in subtle cases)
Add shortcuts for Jackson mix-in annotations registration

This commit adds support for direct Jackson mix-in annotations registration in
Jackson2ObjectMapperFactoryBean and Jackson2ObjectMapperBuilder.

Issue: SPR-12144