Issue: SPR-13992

Issue: SPR-13992

The ResourceHttpRequestHandler now relies on the conifgured
ContentNegotiationManager to determine the content type for resource
requests rather than implementing that internally.

First we check against the matched resource based on the resource file
extension. Then we expand the check against the request with any
configured content negotiation strategy.

Issue: SPR-13658

The DefaulUriTemplateHandler now provides a strictEncoding property
which if turned on encodes everything outside the reserved char set.

This is in contrast to the default policy of encoding only illegal
charaters depending on the URI component type.

Issue: SPR-11652

Issue: SPR-13614

Issue: SPR-13614

The new Filter is simply a new way of packaging the ability to extract
X-Forwarded-* headers already available via UriComponentsBuilder.

The Filter wraps the request and the effect is that anything using the
request will see the original schem, host, and port.

Issue: SPR-13614

Issue: SPR-13975

Prior to this commit, `ServletWebRequest.checkNotModified` would only
support conditional GET/HEAD requests with "If-Modified-Since" and/or
"If-None-Match" request headers. In those cases, the server would return
"HTTP 304 Not Modified" responses if the resource didn't change.

This commit adds support for conditional update requests, such as
POST/PUT/DELETE requests with "If-Unmodified-Since" request headers.
If the underlying resource has been modified since the specified date,
the server will return a "409 Precondition failed" response status
to prevent concurrent updates.

Even if the modification status of the resource is reversed here
(modified vs. not modified), we're keeping here the same intent for the
return value, which signals if the response requires more processing or
if the handler method can return immediately:

```
if (request.checkNotModified(lastModified)) {
  // shortcut exit - no further processing necessary
  return null;
}
```

Issue: SPR-13863

Before this commit, specifying the charset to use with produces or
consumes @RequestMapping attributes resulted in default charset
loss. That was really annoying for JSON for example, where using
UTF-8 charset is mandatory in a lot of use cases.

This commit adds a defaultCharset property to
AbstractHttpMessageConverter in order to avoid losing the
default charset when specifying the charset with these
@RequestMapping attributes.

It changes slightly the default behavior (that's why we have waited
4.3), but it is much more error prone, and will match with most
user's expectations since the charset loss was accidental in most
use cases (users usually just want to limit the media type supported
by a specific handler method).

Issue: SPR-13631

This commit introduces the following common composed annotations for
@RequestMapping in Spring MVC and Spring MVC REST.

- @GetMapping
- @PostMapping
- @PutMapping
- @DeleteMapping
- @PatchMapping

Issue: SPR-13992

This commit introduces the following common composed annotations for
web scopes.

- @RequestScope
- @SessionScope
- @ApplicationScope

Issue: SPR-13993

This commit allows to specify the request body type in order to
serialize generic types with a GenericHttpMessageConverter if
needed.

Issue: SPR-13154

This commit adds weak ETag support in ShallowEtagHeaderFilter.
This improves the behavior of the filter in tow ways:

* weak ETags in request headers such as `W/"0badc0ffee"` will be
compared with a "weak comparison" (matching both weak and strong ETags
of the same value)
* when enabled with the "writeWeakETag" init param, the filter will
write weak Etags in its HTTP responses

Issue: SPR-13778

Issue: SPR-13950

Issue: SPR-13952

This change makes clear that this is the intent of the CacheControl API
not to provide a way to configure both "no-cache" and "no-store"
directives for the "Cache-Control" header.

Issue: SPR-13780

This commit changes the OkHttpClientHttpRequestFactory to use the
synchronous OkHttp API for non-async requests, as opposed to
synchronizing the async API (which it used to do).

Issue: SPR-13942

Issue: SPR-13571

Issue: SPR-13928

Issue: SPR-13929

Issue: SPR-13917

Issue: SPR-13906

Issue: SPR-9712

Issue: SPR-13402

Issue: SPR-13894

Issue: SPR-13894

Consistent java.util.Optional resolution, lenient handling of optional multipart files, correct Servlet 3.0 Part list/array selection

Issue: SPR-13418
Issue: SPR-13849
Issue: SPR-13850
Issue: SPR-13893

AbstractJackson2HttpMessageConverter now implements its own
TypeVariable resolution algorithm since in Jackson 2.7 it is now
deprecated and has not the same behavior .
See https://github.com/FasterXML/jackson-databind/issues/1087
for more details.

The dependency on jackson-datatype-jdk7 has been removed since
it is now provided by default in the jackson-databind module.

Issues: SPR-13483, SPR-13728

Issue: SPR-13130