Prior to this change, `XpathResultMatchers` and more generally the
`MockHttpServletResponse` would default to ISO-8859-1 encoding even when
it's not supposed to. The Servlet/HTTP specs mention this encoding
for all `text/*` mime types when decoding bodies to Strings, but this
issue is about XML Parsers.

XML Parsers should use the encoding:

* defined in the `Content-Type` response header (if available)
* written in the XML declaration of the document
* "guessed" by a built-in auto-detection mechanism

This commit changes the following:

* XPathMatchers now feed the XML parser with byte arrays instead of
decoded Strings
* the response should be written to `MockHttpServletResponse` using
its OutputStream, and not a PrintWriter which defaults to ISO-8859-1

Issue: SPR-12676

This commit improves SPR-13090 and avoids adding duplicate ETag and
Last-Modified headers in HTTP responses.
Previously, those were added twice to the response since:

* we're adding all ResponseEntity headers to the response
* the `checkNotModified` methods automatically add those headers

Issue: SPR-13090

Fixed fallback mode in ObjenesisCglibAopProxy, plus consistent support for bypassing Objenesis (e.g. on Google App Engine)

This 4.2 commit revises SpringObjenesis towards a smart delegate, including support for a "spring.objenesis.ignore" system property.

Issue: SPR-13131

Issue: SPR-13128

Review bd093eb6 to provide a generic type on `JmsResponse`

Issue: SPR-13133

Add JmsResponse that can be used as return type of any JMS listener
method to indicate not only the response but also the actual destination
to which the reply should be sent.

Issue: SPR-13133

Before this change HandlerMethodReturnValueHandler's were invoked in a
specific order (type-based, annotation-based, custom). However handlers
that deal with asynchronous return value handling need to always be
considered first. This affects custom handlers in particular since they
are normally ordered last.

This change introduces an AsyncHandlerMethodReturnValueHandler
sub-interface with a single method to determine if the return value is
asynchronous and if it is to look for a matching handler only among
those that are of type AsyncHandlerMethodReturnValueHandler.

Issue: SPR-13083

Issue: SPR-13078

This commit introduces the following changes in AbstractHandlerExceptionResolver:
 - warnLogger used to log exception is enabled by default
 - the exception message is now logged instead of the whole exception stacktrace
 - warn logging is only performed if doResolveException() returns a non-null
   ModelAndView, in order to avoid logging multiple times the error

Issue: SPR-13100

Before this change a missing path variable value resulted in a 400
error where in fact the error is due to a mismatch between the
declared @PathVariable and the URI template, i.e. a 500 error.

This change introduced a MissingPathVariableException as a sub-class
of ServletRequestBindingException (the exception previously thrown)
and results in a response status code of 500 by default.

Issue: SPR-13121

Issue: SPR-13128

Issue: SPR-13093

* patch-3:
  Add missing super in test

Closes gh-814

This is a rework of 71783c5d for SPR-12540 for the async extension that
was not merging the internal RequestConfig as it should.

Issue: SPR-13125

Issue: SPR-11807

Issue: SPR-13099

Issue: SPR-13115

Issue: SPR-13129

Ever since @ActiveProfiles was introduced, the declared active profiles
for integration tests have been sorted in order to support unique cache
key generation; however, there are use cases for which the original
ordering should be retained.

For example, Spring Boot's ConfigFileApplicationListener loads
configuration files for active profiles in the order returned by
Environment.getActiveProfiles(), with the assumption that the ordering
matches the order in which the developer declared the active profiles.

This commit maintains the uniqueness of active profiles declared via
@ActiveProfiles but no longer sorts them.

Issue: SPR-12492

Issue: SPR-12991

Issue: SPR-13041

Issue: SPR-13069

In AnnotatedElementUtils, all methods pertaining to merging annotation
attributes have been renamed to "getMerged*()" and "findMerged*()"
accordingly. Existing methods such as getAnnotationAttributes(..) have
been deprecated in favor of the more descriptive "merged" variants.
This aligns the naming conventions in AnnotatedElementUtils with those
already present in AnnotationReadingVisitorUtils.

The use of "annotationType" as a variable name for the fully qualified
class name of an annotation type has been replaced with
"annotationName" in order to improve the readability and intent of the
code base.

In MetaAnnotationUtils.AnnotationDescriptor, getMergedAnnotation() has
been renamed to synthesizeAnnotation(), and the method is now
overridden in UntypedAnnotationDescriptor to always throw an
UnsupportedOperationException in order to avoid potential run-time
ClassCastExceptions.

Issue: SPR-11511

- origin --> origins
- method --> methods
- constants are now actually constant (i.e., static final)