This commit introduces the following methods in JsonPathResultMatchers
in the Spring MVC Test framework.

- isString()
- isBoolean()
- isNumber()
- isMap()

In addition, this commit overhauls the Javadoc in
JsonPathResultMatchers and JsonPathExpectationsHelper.

Issue: SPR-13320

This commit aims to improve the space and time performance of
NumberUtils by invoking valueOf() factory methods instead of the
corresponding constructors when converting a number to a target class.

Prior to this commit, an explicit override for an attribute in a
meta-annotation configured via @AliasFor could potentially result in an
incorrect override of an attribute of the same name but in the wrong
meta-annotation.

This commit fixes the algorithm in getAliasedAttributeName(Method,
Class) in AnnotationUtils by ensuring that an explicit attribute
override is only applied to the configured target meta-annotation
(i.e., configured via the 'annotation' attribute in @AliasFor).

Issue: SPR-13325

Issue: SPR-13297

Issue: SPR-13300

* pr/851:
  Remove type parameter of ResponseBodyEmitter

Closes gh-851

Issue: SPR-11515

Issue: SPR-11515

Issue: SPR-13295

This change ensures that an onError outcome from an async request is
also routed to onCompletion handlers registered with
StandardServletAsyncWebRequest.

Issue: SPR-13292

Prior to this commit, the `ResponseStatusExceptionResolver` would use:
* `HttpServletResponse.sendError` if both a status and a reason are set
on the `@ResponseStatus` annotation
* `HttpServletResponse.setStatus` if only a status is set on the
`@ResponseStatus` annotation

This is actually a change of behavior, since this Resolver was using
`sendError` in all cases previously.

Because this change can create issues such as
https://github.com/spring-projects/spring-boot/issues/3623
this commit rollbacks those changes and clarifies the behavior on the
javadoc of the annotation itself.

Issue: SPR-11193, SPR-13226

Issue: SPR-13125

Issue: SPR-13293

Issue: SPR-13037

Issue: SPR-12839

Issue: SPR-13289

SPR-11512 introduced support for annotation attribute aliases via
@AliasFor, requiring the explicit declaration of the 'attribute'
attribute. However, for aliases within an annotation, this explicit
declaration is unnecessary.

This commit improves the readability of alias pairs declared within an
annotation by introducing a 'value' attribute in @AliasFor that is an
alias for the existing 'attribute' attribute. This allows annotations
such as @ContextConfiguration from the spring-test module to declare
aliases as follows.

public @interface ContextConfiguration {

     @AliasFor("locations")
     String[] value() default {};

     @AliasFor("value")
     String[] locations() default {};

    // ...
}

Issue: SPR-13289

Issue: SPR-12970
Issue: SPR-13285

Issue: SPR-13257

Issue: SPR-13286