Prior to this commit, attempting to synthesize an annotation from a map
of annotation attributes that contained nested maps instead of nested
annotations would result in an exception.

This commit addresses this issue by properly synthesizing nested maps
and nested arrays of maps into nested annotations and nested arrays of
annotations, respectively.

Issue: SPR-13338

It is a configuration error if an alias is declared via @AliasFor for
an attribute in a meta-annotation and the meta-annotation is not
meta-present. However, prior to this commit, the support for validating
the configuration of @AliasFor in AnnotationUtils currently silently
ignored such errors.

This commit fixes this by throwing an AnnotationConfigurationException
whenever a required meta-annotation is not present or meta-present on
an annotation that declares an explicit alias for an attribute in the
meta-annotation.

Issue: SPR-13335

Prior to this commit, MockHttpServletRequestBuilder always supplied an
array of cookies to the MockHttpServletRequest that it built, even if
the array was empty.

However, this violates the contract of HttpServletRequest. According to
the Servlet API, the getCookies() method "returns null if no cookies
were sent."

This commit ensures that MockHttpServletRequestBuilder no longer
configures an empty array of cookies in the mock request that it builds.

Issue: SPR-13314

* SPR-13320:
  Introduce additional JsonPath matchers in Spring MVC Test

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