Issue: SPR-12266

CorsConfiguration now provides methods to check and determine the
allowed origin, method, and headers according to its own configuration.

This simplifies significantly the work that needs to be done from
DefaultCorsProcessor. However an alternative CorsProcessor can still
access the raw CorsConfiguration and perform its own checks.

Issue: SPR-12885

This commit adds CORS related headers to HttpHeaders
and update DefaultCorsProcessor implementation to
use ServerHttpRequest and ServerHttpResponse instead
of HttpServletRequest and HttpServletResponse. Usage
of ServerHttpResponse allows to avoid using Servlet 3.0
specific methods in order keep CORS support Servlet 2.5
compliant.

Issue: SPR-12885

The change to provide public register/unregister methods in
AbstractHandlerMethodMapping assumed that a single method cannot be
mapped more than once. This is not the case with the MvcEndpoints and
EndpointHandlerMapping from Spring Boot which wrap one or more
non-web Endpoint types with an MvcEndpointAdapter in order to expose
them for use over the web. In effect Spring MVC sees a single handler
method mapped many times.

This change removes that assumption so rather than unregistering with
a HandlerMethod, which is not necessarily unique, the unregister method
now takes the actual mapping, which is the only thing that should actually
be unique.

Issue: SPR-11541

Issue: SPR-12977

Issue: SPR-12962

Issue: SPR-11514

Issue: SPR-12469

This commit adds additional context to the exception message generated
when two candidate methods are discovered in MvcUriComponentsBuilder's
getMethod(Class<?>, String, Object...).

Issue: SPR-12977

This commit introduces a new fromMethodNameWithBridgedMethod() test in
MvcUriComponentsBuilderTests which is currently disabled via @Ignore
until this bug is resolved.

Issue: SPR-12977

When used in combination with GzipResourceResolver, the
CachingResourceResolver does not properly cache results, since it only
takes the request path as a input for cache key generation.

Here's an example of that behavior:

1. an HTTP client requests a resource with `Accept-Encoding: gzip`, so
the GzipResourceResolver can resolve a gzipped resource.
2. the configured CachingResourceResolver caches that resource.
3. another HTTP client requests the same resource, but it does not
support gzip encoding; the previously cached gzipped resource is still
returned.

This commit uses the presence/absence of gzip encoding support as an
input in cache keys generation.

Issue: SPR-12982

Issue: SPR-11541

Issue: SPR-11541

Before this change AbstractHandlerMethodMapping contained multiple
maps all containing different kinds of mapping meta-data. After the
change a MappingDefinitionRegistry inner class encapsulates these
fields along with their initialization code.

Issue: SPR-11541

Issue: SPR-11541

Issue: SPR-12960

Issue: SPR-12956

Issue: SPR-12955

Issue: SPR-12969

This commit fixes recent build failures involving
MessageBrokerBeanDefinitionParserTests and NoClassDefFoundError:
io/netty/channel/nio/NioEventLoopGroup.

This commit documents the status quo for the getMetaAnnotationTypes()
method in AnnotatedElementUtils and adds appropriate regression tests to
AnnotatedElementUtilsTests.

In addition, this commit also introduces a SimpleAnnotationProcessor
base class in AnnotatedElementUtils.

Issue: SPR-11514

This commit documents return values throughout AnnotatedElementUtils and
improves the documentation for the internal Processor API.

Issue: SPR-11514

Prior to this commit it was possible for two @BootstrapWith annotations
to be 'present' on a test class -- for example, via competing custom
composed annotations. However, only one of the annotations will ever be
used to bootstrap the TestContext Framework. Thus, in such scenarios
one of the annotations will be silently ignored.

This commit introduces a check for such scenarios. BootstrapUtils'
resolveTestContextBootstrapper() method now throws an
IllegalStateException if more than one @BootstrapWith annotation is
'present' on a given test class.

Issue: SPR-12602

Issue: SPR-12932

Issue: SPR-12738

This commit consistently documents the 'element' and 'annotationType'
method arguments throughout AnnotatedElementUtils.

In addition, this commit introduces assertions against preconditions
for all 'element' and 'annotationType' method arguments.

Issue: SPR-11514

Previously MockHttpServletRequestBuilder merge method would append the
parent's (default) RequestPostProcessor implementations to the end. This
means that the default RequestPostProcessor implementations would override
values set by previous RequestPostProcessor implementations.

This commit ensures that the default RequestPostProcessor are preformed
first so that additional RequestPostProcessor implementations override
the defaults.

Issue: SPR-12945

Issue: SPR-12928

Issue: SPR-12296