Issue: SPR-14765

Issue: SPR-14743

Prior to this commit, the `HttpEntityMethodProcessor` would avoid
writing ETag/Last-Modified response headers before calling
`ServletWebRequest` to process conditional requests. This was done to
avoid duplicate response header values due to headers being already
written to the underlying servlet response.

This is still necessary for GET/HEAD requests, since this is properly
handled by `ServletWebRequest` for those cases. But
`HttpEntityMethodProcessor` should not make that decision for
PUT/PATCH/POST responses since developers are adding response headers on
purpose and should be in control of the situation — whereas
`ServletWebRequest` does not write those headers in those cases.

Issue: SPR-14767

Prior to this commit, the PrintingResultHandler used by the various
print() and log() methods in Spring MVC Test printed the response body
but not the request body.

Since request bodies are sometimes generated programmatically, however,
it can be beneficial to have the dynamically generated request body
logged as well.

This commit therefore prints the request body in PrintingResultHandler
by delegating to the recently introduced getContentAsString() method in
MockHttpServletRequest.

Issue: SPR-14717

In order to improve debugging and logging within test suites, this
commit introduces getContentAsByteArray() and getContentAsString()
methods in MockHttpServletRequest, analogous to the existing methods in
MockHttpServletResponse.

Issue: SPR-14717

This commit refine Jackson canEncode() / canDecode()
implementation by using ObjectMapper canSerialize() /
canDeserialize() methods.

Issue: SPR-14748

Issue: SPR-14748

Issue: SPR-14748

Issue: SPR-14747

Issue: SPR-14749

Issue: SPR-14737

Improve performance of StompEncoder

Issue: SPR-14747

Fixes SPR-14747

this PR fixes the spelling error for the word 'recommendation'

This commit adds a new chain-based, interception contract to be used
with `WebClient`. This is the HTTP client equivalent of the `WebFilter`
contract already implemented in web reactive server.

A `ClientHttpRequestInterceptor` implementation can transform the
outgoing HTTP request (method, URI or headers) before delegating it to
the next interceptor in the chain, or bypass the request processing
altogether and return a (cached) HTTP response.

Issue: SPR-14502

This commit also removes the ServerHttpResponse parameter, not
needed here since it is possible to override the write() method.

Issue: SPR-14557

This commit handles range requests in `ResourceWebHandler`, using the
`ResourceHttpMessageWriter` configured within the handler.

This `WebHandler` will add a `HTTP_RANGE_REQUEST_HINT` writer hint
containing all the HTTP Range information of the request.

Issue: SPR-14664

This new `HttpMessageWriter` leverages the `ResourceRegionEncoder` to
write `ResourceRegion` to HTTP responses, thus supporting HTTP Range
requests.

Whenever possible, this message writer uses the zero copy support for
single range requests.

This `HttpMessageWriter` is never used directly, but is used as a
delegate by the `ResourceHttpMessageWriter`. When provided with the
`BOUNDARY_STRING_HINT`, the `ResourceRegionHttpMessageWriter`
adapts its behavior in order to write a single/multiple byte ranges.

Issue: SPR-14664

This commit adds the necessary infrastructure for the support of HTTP
Range requests. The new `ResourceRegionEncoder` can write
`ResourceRegion` objects as streams of bytes.

The `ResourceRegionEncoder` relies on an encoding hint
`BOUNDARY_STRING_HINT`. If present, the encoder infers that multiple
`ResourceRegion`s should be encoded and that the provided boundary
String should be used to separate ranges by mime boundaries.
If that hint is absent, only a single resource region is encoded.

Issue: SPR-14664

This commit makes it possible, in addition to provide hints, to
perform additional operations with the request and the response
at ServerHttpMessageReader/Writer level.

AbstractServerHttpMessageReader/Writer now provide
convenient beforeRead/beforeWrite abstract methods for such need.

Issue: SPR-14557

Issue: SPR-14557

Issue: SPR-14735