AbstractAutoProxyCreator and AbstractAdvisingBeanPostProcessor consistently not considering configuration callbacks and internal language interfaces as reasonable proxy interfaces

Issue: SPR-11715

AbstractAdvisingBeanPostProcessor uses target class check for existing proxy but checks against actual exposed object otherwise (catching introductions)

Issue: SPR-11725

Issue: SPR-9335

Clean up compiler warnings in the tests of spring-aop. This commit
adds type parameters to all the types.

Issue: SPR-11618

Prior to this commit, an exception thrown by an @Async void method
was not further processed as there is no way to transmit that
exception to the caller.

The AsyncUncaughtExceptionHandler is a new strategy interface that
can be implemented to handle unexpected exception thrown during the
invocation of such asynchronous method.

The handler can be specified using either the XML namespace or by
implementing the AsyncConfigurer interface with the EnableAsync
annotation.

Issue: SPR-8995

This commit rationalizes the use of @order so that the standard
@Priority annotation can be used instead. The handling of both
annotations are now defined in OrderUtils.

This also updates the link to the JavaEE API so that we refer to
JavaEE7 instead of JavaEE6.

Issue: SPR-11639

Prior to this commit, the codebase was using a mix of log4j.xml
and log4j.properties for test-related logging configuration. This
can be an issue as log4j takes the xml variant first when looking
for a default bootstrap configuration.

In practice, some modules declaring the properties variant were
taking the xml variant configuration from another module.

The general structure of the configuration has also been
harmonized to provide a standard console output as well as an
easy way to enable trace logs for the current module.

Issue: SPR-11416

- Consistent importing of org.junit.Assert.*;
- Proper declaration of expected exceptions via @test(expected).
- Renamed SpEL ExpressionTestCase to AbstractExpressionTests.
- Formatting and test method naming conventions.

Issue: SPR-11398

Issue: SPR-11344
(cherry picked from commit d434ef97)

Fixed through downcasting to AspectJ's ReflectionType and ReflectionBasedReferenceTypeDelegate, obtaining the myClass field there. We only fall back to regular class loading if we encounter any other kind of type.

Issue: SPR-11344
(cherry picked from commit c406c56d)

Issue: SPR-10886
Issue: SPR-7342

Issue: SPR-11330

Consistent equals/hashCode/toString implementations in AnnotationMatchingPointcut/ClassFilter/MethodMatcher

Issue: SPR-11275
Issue: SPR-11276

This allows scoped proxy definitions to override regular application bean definitions (again).

Issue: SPR-11229

Issue: SPR-11107

Issue: SPR-11116

Update code to have a consistent number of new-line characters after
import statements.

Fix a variety of typos throughout the project, primarily in
comments (javadoc or otherwise) but also in a handful of log messages
and a couple exception messages.

ISSUE: SPR-11123

Fix remaining Java compiler warnings, mainly around missing
generics or deprecated code.

Also add the `-Werror` compiler option to ensure that any future
warnings will fail the build.

Issue: SPR-11064

Issue: SPR-10430

Issue: SPR-10834

Extended DefaultAopProxyFactory to create Objenesis based proxies if the
library is on the classpath. This allows classes without a default
constructor being CGLib proxied. We're now falling back to original CGLib
based behavior in case the proxy creation using Objenesis fails.

Objenesis 2.0 is now inlined into spring-core to avoid interfering with
other Objenesis versions on the classpath.

Issue: SPR-10594

Also fixing an old XmlBeanFactory test that relies on "ref local" which is gone in the 4.0 xsd now, redeclaring the affected file to an older xsd version.

Introduced  DefaultParameterNameDiscoverer which checks JDK 8's standard reflection first and then falls back to ASM-based debug symbol analysis

Also, StandardReflectionParameterNameDiscoverer calls "Parameter.isNamePresent()" now to return null (and pass on to the next discoverer) if no JDK 8 parameters are available. Note that this requires OpenJDK 8 b100 or higher to compile now.

Issue: SPR-10532