This commit fixes an issue where DataBufferUtils.join() would not
release databuffers that preceded an error signal.

Issue: SPR-17025

Issue: SPR-17198

Issue: SPR-17191

Includes caching of declared annotation arrays and combined searching for several annotation types (used in SpringCacheAnnotationParser).

Issue: SPR-16933

Includes Java 8 getDeclaredAnnotation shortcut for lookup on Class.

Issue: SPR-17146

Issue: SPR-17136

Issue: SPR-16933

Issue: SPR-17188

Includes consistent (non-)use of AnnotationUtils/AnnotatedElementUtils.

Issue: SPR-16933

This revision considers any java/javax and org.springframework.lang annotations as not synthesizable upfront, checking not only in isSynthesizable but also at synthesizeAnnotation(Array) level.

Issue: SPR-16933

Empty Maps are preferably initialized without capacity (not initializing them at all or lazily initializing with default capacity when needed).

Issue: SPR-17105

Issue: SPR-17090

Issue: SPR-17086

Issue: SPR-17012

This commit includes an optimization of BeansUtils#instantiateClass
that favors Java reflection for default constructors before leveraging
Kotlin one for finding primary constructors and avoids Kotlin related
conditions when running in Java.

Issue: SPR-17069

This revision limits serializability of derived interfaces, superclasses and type parameters, optimizing for introspection performance instead.

Issue: SPR-17070

Issue: SPR-16946

Issue: SPR-17064

Issue: SPR-16060

When compiling or running as a Graal native image, no
ParameterNameDiscoverer is used.

Issue: SPR-17005

Like CookieLocaleResolver, LocaleChangeInterceptor parses both locale formats by default now. Since it does not need to render the locale, its languageTagCompliant property is not relevant anymore at all.

The parseLocale method in StringUtils validates the locale value now and turns an empty locale into null, compatible with parseLocaleString behavior and in particular aligned with web locale parsing needs.

Issue: SPR-16700
Issue: SPR-16651

Issue: SPR-17046

Issue: SPR-17029

Issue: SPR-17012

Issue: SPR-16894

Issue: SPR-16966

Issue: SPR-17000

In order to allow Spring Framework applications running as GraalVM
native images, ReactiveAdapterRegistry should perform explicit class
checks instead of catching Throwable in order to avoid
UnsupportedFeatureError errors.

Issue: SPR-17000