* pr/1804:
  Fix typo

Closes gh-1804

Issue: SPR-16655

Issue: SPR-16752

Prior to this commit, the `AbstractMessageConverterMethodProcessor`
would fail to convert `InputStreamResource` to `ResourceRegion` as
expected, since the content length cannot be read without consuming the
stream. This is enforced by the `HttpRange` class.

Now the method processor would still try to output HTTP range response
headers to provide range support information. This step is using the
resource content length and reads the input stream, leading to
exceptions such as "IllegalStateException: InputStream has already been
read".

This commit improves the return type detection and excludes early
`InputStreamResource` return types. With those types, HTTP range support
is now completely disabled.

Issue: SPR-16754

* pr/1803:
  Fix typo

See gh-1803

See gh-1799

ServerSentEventHttpMessageReader had logic to split on new lines
and buffer until an empty new line (start of a new event). To account
for random data chunking, it later re-assembled the lines for each
event and split again on new lines. However bufferUntil was still
unreliable a chunk may contain nothing but a newline, which doesn't
necessarily mean an empty newline in the overall SSE stream.

This commit simplifies the above by delegating the splitting of the
stream along newlines to StringDecoder.

Issue: SPR-16744

Issue: SPR-16726

Issue: SPR-16739

Issue: SPR-16730

Prior to this commit, due to KT-5464 type inference issue there was not
proper way to provide body expectations with WebTestClient. This commit
provides a workaround by updating the existing Kotlin extension to
return a Kotlin compatible API.

Issue: SPR-15692

Issue: SPR-16734

Issue: SPR-16734

Issue: SPR-16731

Issue: SPR-16733

Issue: SPR-16732

Issue: SPR-16728

Includes efficient check for same ClassLoader in ClassUtils.isVisible, efficient MethodMatchers check for IntroductionAwareMethodMatcher, and supertype method resolution in MethodMapTransactionAttributeSource.

Issue: SPR-16723

* pr/1791:
  Fix typo in javadoc

Closes gh-1791

Prior to this commit, the various `HttpMessageConverter` instances
configured for a given `RestTemplate` instance could all contribute
`MediaType` values to the "Accept:" request header.

This could lead to duplicate media types in that request header,
cluttering for the HTTP request for no reason.

This commit ensures that only distinct values are added to the request.

Issue: SPR-16690

Issue: SPR-16714

Issue: SPR-16714

Issue: SPR-16720