Fix a regression introduced by 961574bd that prevents a proper lookup
of the default transaction manager by name as the absence of a qualifier
is represented by an empty string (passing the faulty null check).

Issue: SPR-12577

Fixes #708

Prior to this commit, some requests would be wrongly mapped to "/" when:

* requests ends with "//" such as "/foo/bar//"
* the DispatcherServlet is mapped as the default ("/")
* the app container sanitizes the servletPath

In those cases, the path extraction algorithm was wrongly guessing the
path of the current request.

This commit detects if the app container sanitized the servletPath for
the current request. If so, it uses a sanitized version of the
requestUri to extract the path information.

Issue: SPR-12372

This commit suppresses warnings in test classes that were polluting the
Gradle build output.

(cherry picked from commit 8c700b19)

Issue: SPR-12578

Issue: SPR-12369

Issue: SPR-12214

Issue: SPR-11895

Issue: SPR-12502

Issue: SPR-12545

The following two refinements have been added:
1) SockJS doesn't support binary messages so don't even try
2) don't bother if payload.length == 0

Issue: SPR-12475

Issue: SPR-12575

Issue: SPR-12523

Issue: SPR-12574

AnnotationJmxAttributeSource uses AnnotationUtils for consistent meta-annotation handling and diagnostics

Issue: SPR-12572

Issue: SPR-12567

Issue: SPR-12570

Align default aop.xml configuration to define the JCache aspect alongside
the regular Spring cache aspect.

 Issue: SPR-12571

Previously the default settings of a custom HttpClient were always
ignored since a RequestConfig instance was always set no matter if
some customizations were applied or not.

This commit keeps an internal RequestConfig object instance that is
only initialized if the user applies a customization. If he does not, the
default settings of the HttpClient are used as it should.

Note that if the HttpComponents API exposed the default RequestConfig
of a given HttpClient, we would be able to merge our customizations with
the one specified by the client. Unfortunately, such API does not exist
and the "defaultSettingsOfHttpClientLostOnExecutorCustomization" test
illustrates that limitation.

Issue: SPR-12540

One more (and hopefully last) attempt at making sure
determineTransactionManager does not break existing use cases.

This commit prevents any lookup if no transaction attributes are set
which is more compliant with the original version and prevents a lookup
if a non existing bean name is provided explicitly (as it can be the case
with Spring Boot).

Issue: SPR-12541

The fix in cec26e9a for SPR-12541 actually introduced a regression
when the interceptor is enabled on a method that does not require any
transaction. In such a case we try to locate the default
PlatformTransactionManager instead of just returning what we have (that
is null).

This commit updates the determineTransactionManager condition again to
take that use case into account again.

Issue: SPR-12541

In order to avoid breaking changed due to the upcoming SockJS 1.0
release (see SPR-12422 for more details) and link to the right
SockJS documentation version, we now explicitly specify that we
support SockJS protocol 0.3.3 and SockJS client 0.3.x.

Before this change attributes listed with @SessionAttributes would not
be saved in the session when there was a redirect and the controller
method declared a parameter of type RedirectAttributes.

This change ensures it's the "default" model that is always the one
checked for @SessionAttributes under all circumstances since
RedirectAttributes is really only meant to provide String values to
insert into or append to the the redirect URL.

Issue: SPR-12542

After this change the StompSubProtocolHandler sends STOMP frames
with content-type=octet-stream as a binary WebSocket message.

Issue: SPR-12475

HandlerExecutionChain prevents re-adding the interceptors array to the list (and declares varargs now)

Issue: SPR-12566

Issue: SPR-12543

Previously, if a bean has a scoped proxy and is annotated to be exposed
to the JMX domain, both the scoped proxy and the target instance were
exposed in the JMX domain, resulting in a duplicate entries. Worse, if
such bean defines an explicit name, the application wouldn't start
because of a name conflict.

This commit deals explicitely with scoped proxy and make sure to only
expose the relevant bean.

Issue: SPR-12529

Issue: SPR-12526

Issue: SPR-12522

Issue: SPR-12565