Prior to this commit, the implementation of getRepeatableAnnotation()
in Spring's AnnotationUtils complied neither with the contract of
getAnnotationsByType() nor with the contract of
getDeclaredAnnotationsByType() as defined in AnnotatedElement in Java 8.

Specifically, unexpected results can be encountered when using Spring's
support for @Repeatable annotations: either annotations show up in the
returned set in the wrong order, or annotations are returned in the set
that should not even be found based on the semantics of @Repeatable.

This commit remedies this problem by deprecating the existing
getRepeatableAnnotation() methods and replacing them with new
getRepeatableAnnotations() and getDeclaredRepeatableAnnotations()
methods that comply with the contracts of Java's getAnnotationsByType()
and getDeclaredAnnotationsByType(), respectively.

Issue: SPR-13068

The initial support for synthesizing an annotation from a Map (or
AnnotationAttributes) introduced in SPR-13067 required that the map
contain key-value pairs for every attribute defined by the supplied
annotationType. However, there are use cases that would benefit from
being able to supply a reduced set of attributes and still have the
annotation synthesized properly.

This commit refines the validation mechanism in
MapAnnotationAttributeExtractor so that a reduced set of attributes may
be supplied. Specifically, if an attribute is missing in the supplied
map the attribute will be set either to value of its alias (if an alias
value configured via @AliasFor exists) or to the value of the
attribute's default value (if defined), and otherwise an exception will
be thrown.

Furthermore, TransactionalTestExecutionListener has been refactored to
take advantage of this new feature by synthesizing an instance of
@TransactionConfiguration solely from the default values of its
declared attributes.

Issue: SPR-13087

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

Issue: SPR-11393

Provide a mean to detect the actual ResolvableType based on a instance as
a counter measure to type erasure.

Upgrade the event infrastructure to detect if the event (or the payload)
implements such interface. When this is the case, the return value of
`getResolvableType` is used to validate its generic type against the
method signature of the listener.

Issue: SPR-13069

Issue: SPR-11393

Issue: SPR-11393

This commit introduces a "synthesized annotation" alternative to
getAnnotationAttributes() in AnnotatedElementUtils, analogous to the
recently introduced findAnnotation() methods.

Issue: SPR-13082

Issue: SPR-13084

Spring Framework 4.2 RC1 introduced support for synthesizing an
annotation from an existing annotation in order to provide additional
functionality above and beyond that provided by Java. Specifically,
such synthesized annotations provide support for @AliasFor semantics.
As luck would have it, the same principle can be used to synthesize an
annotation from any map of attributes, and in particular, from an
instance of AnnotationAttributes.

The following highlight the major changes in this commit toward
achieving this goal.

- Introduced AnnotationAttributeExtractor abstraction and refactored
  SynthesizedAnnotationInvocationHandler to delegate to an
  AnnotationAttributeExtractor.

- Extracted code from SynthesizedAnnotationInvocationHandler into new
  AbstractAliasAwareAnnotationAttributeExtractor and
  DefaultAnnotationAttributeExtractor implementation classes.

- Introduced MapAnnotationAttributeExtractor for synthesizing an
  annotation that is backed by a map or AnnotationAttributes instance.

- Introduced a variant of synthesizeAnnotation() in AnnotationUtils
  that accepts a map.

- Introduced findAnnotation(*) methods in AnnotatedElementUtils that
  synthesize merged AnnotationAttributes back into an annotation of the
  target type.

The following classes have been refactored to use the new support for
synthesizing AnnotationAttributes back into an annotation.

- ApplicationListenerMethodAdapter
- TestAnnotationUtils
- AbstractTestContextBootstrapper
- ActiveProfilesUtils
- ContextLoaderUtils
- DefaultActiveProfilesResolver
- DirtiesContextTestExecutionListener
- TestPropertySourceAttributes
- TestPropertySourceUtils
- TransactionalTestExecutionListener
- MetaAnnotationUtils
- MvcUriComponentsBuilder
- RequestMappingHandlerMapping

In addition, this commit also includes changes to ensure that arrays
returned by synthesized annotations are properly cloned first.

Issue: SPR-13067

Prior to this commit, when a nested array of annotations was
synthesized while adapting values within an AnnotationAttributes map,
the array was improperly replaced with an array of type Annotation[]
instead of an array of the concrete annotation type, which can lead to
unexpected run-time exceptions.

This commit fixes this bug by replacing annotations in the existing
array with synthesized versions of those annotations, thereby retaining
the original array's component type.

Issue: SPR-13077

This commit introduces support in AnnotationAttributes for retrieving
nested annotations that is on par with the existing type-safe support
for retrieving nested AnnotationAttributes.

Issue: SPR-13074

AnnotationAttributes has existed for several years, but none of the
"get" methods that make up its public API are documented. In many
cases, the behavior can be inferred from the name of the method, but
for some methods there are "hidden gems" and unexpected behavior
lurking behind the scenes.

This commit addresses this issue by documenting all public methods. In
addition, the hidden support for converting single elements into
single-element arrays has also been documented and tested.

Issue: SPR-13072

Issue: SPR-13066

Issue: SPR-13065

Issue: SPR-13064

This commit introduces a test that will fail if SynthesizedAnnotation is
not public as is required by the contract for getProxyClass() in
java.lang.reflect.Proxy.

Issue: SPR-13057

Includes an optimization for simple ByteBuffer duplication.

Issue: SPR-13056

This commit introduces first-class support for aliases for annotation
attributes. Specifically, this commit introduces a new @AliasFor
annotation that can be used to declare a pair of aliased attributes
within a single annotation or an alias from an attribute in a custom
composed annotation to an attribute in a meta-annotation.

To support @AliasFor within annotation instances, AnnotationUtils has
been overhauled to "synthesize" any annotations returned by "get" and
"find" searches. A SynthesizedAnnotation is an annotation that is
wrapped in a JDK dynamic proxy which provides run-time support for
@AliasFor semantics. SynthesizedAnnotationInvocationHandler is the
actual handler behind the proxy.

In addition, the contract for @AliasFor is fully validated, and an
AnnotationConfigurationException is thrown in case invalid
configuration is detected.

For example, @ContextConfiguration from the spring-test module is now
declared as follows:

    public @interface ContextConfiguration {

        @AliasFor(attribute = "locations")
        String[] value() default {};

        @AliasFor(attribute = "value")
        String[] locations() default {};

        // ...
    }

The following annotations and their related support classes have been
modified to use @AliasFor.

- @ManagedResource
- @ContextConfiguration
- @ActiveProfiles
- @TestExecutionListeners
- @TestPropertySource
- @Sql
- @ControllerAdvice
- @RequestMapping

Similarly, support for AnnotationAttributes has been reworked to
support @AliasFor as well. This allows for fine-grained control over
exactly which attributes are overridden within an annotation hierarchy.
In fact, it is now possible to declare an alias for the 'value'
attribute of a meta-annotation.

For example, given the revised declaration of @ContextConfiguration
above, one can now develop a composed annotation with a custom
attribute override as follows.

    @ContextConfiguration
    public @interface MyTestConfig {

        @AliasFor(
           annotation = ContextConfiguration.class,
           attribute = "locations"
        )
        String[] xmlFiles();

        // ...
    }

Consequently, the following are functionally equivalent.

- @MyTestConfig(xmlFiles = "test.xml")
- @ContextConfiguration("test.xml")
- @ContextConfiguration(locations = "test.xml").

Issue: SPR-11512, SPR-11513

ByteBufferConverter also defensively returns the rewind result now.

Issue: SPR-13031

Provide Converter implementations for Charset, Currency and TimeZone as
related PropertyEditors are available for those.

Issue: SPR-13020

This commit updates the "get semantics" search algorithm used in
`AnnotatedElementUtils` so that locally declared 'composed annotations'
are favored over inherited annotations.

Specifically, the internal `searchWithGetSemantics()` method now
searches locally declared annotations before searching inherited
annotations.

All TODOs in `AnnotatedElementUtilsTests` have been completed, and all
ignored tests have been reinstated.

Issue: SPR-11598

(cherry picked from commit 9e925aa8)

Issue: SPR-13007

Prior to this commit, the `getAnnotation()` method in `TypeDescriptor`
only supported a single level of meta-annotations. In other words, the
annotation hierarchy would not be exhaustively searched.

This commit provides support for arbitrary levels of meta-annotations
in `TypeDescriptor` by delegating to `AnnotationUtils.findAnnotation()`
within `TypeDescriptor.getAnnotation()`.

Issue: SPR-12793

Issue: SPR-11514

Issue: SPR-11514

Issue: SPR-11514

This commit picks up where SPR-11483 left off, with the goal of
eliminating all unnecessary inspection of core JDK annotations in
Spring's annotation search algorithms in AnnotatedElementUtils and
AnnotationMetadataReadingVisitor.

Issue: SPR-12989

 - Methods which search for a specific annotation now properly ensure
   that the sought annotation was actually found.

 - Both the "get" and the "find" search algorithms no longer needlessly
   traverse meta-annotation hierarchies twice.

 - Both the "get" and the "find" search algorithms now properly
   increment the metaDepth when recursively searching within the
   meta-annotation hierarchy.

 - Redesigned getMetaAnnotationTypes() so that it doesn't needlessly
   search irrelevant annotations.

 - Documented and tested hasMetaAnnotationTypes().

 - Documented isAnnotated().

Issue: SPR-11514

This commit documents the status quo for the getMetaAnnotationTypes()
method in AnnotatedElementUtils and adds appropriate regression tests to
AnnotatedElementUtilsTests.

In addition, this commit also introduces a SimpleAnnotationProcessor
base class in AnnotatedElementUtils.

Issue: SPR-11514

Issue: SPR-12738