Issue: SPR-13393
(cherry picked from commit 302a0692)

Issue: SPR-13393

Issue: SPR-13554

Issue: SPR-13542

This commit migrates all remaining tests from JUnit 3 to JUnit 4, with
the exception of Spring's legacy JUnit 3.8 based testing framework that
is still in use in the spring-orm module.

Issue: SPR-13514

Issue: SPR-13509

This commit picks up where 3eacb837
(SPR-13345) left off by adding support for transitive implicit aliases
configured via @AliasFor.

Issue: SPR-13405

Spring Framework 4.2 introduced support for aliases between annotation
attributes that fall into the following two categories.

1) Alias pairs: two attributes in the same annotation that use
   @AliasFor to declare that they are explicit aliases for each other.
2) Meta-annotation attribute overrides: an attribute in one annotation
   uses @AliasFor to declare that it is an explicit override of an
   attribute in a meta-annotation.

However, the existing functionality fails to support the case where two
attributes in the same annotation both use @AliasFor to declare that
they are both explicit overrides of the same attribute in the same
meta-annotation. In such scenarios, one would intuitively assume that
two such attributes would be treated as "implicit" aliases for each
other, analogous to the existing support for explicit alias pairs.
Furthermore, an annotation may potentially declare multiple aliases
that are effectively a set of implicit aliases for each other.

This commit introduces support for implicit aliases configured via
@AliasFor through an extensive overhaul of the support for alias
lookups, validation, etc. Specifically, this commit includes the
following.

- Introduced isAnnotationMetaPresent() in AnnotationUtils.

- Introduced private AliasDescriptor class in AnnotationUtils in order
  to encapsulate the parsing, validation, and comparison of both
  explicit and implicit aliases configured via @AliasFor.

- Switched from single values for alias names to lists of alias names.

- Renamed getAliasedAttributeName() to getAliasedAttributeNames() in
  AnnotationUtils.

- Converted alias map to contain lists of aliases in AnnotationUtils.

- Refactored the following to support multiple implicit aliases:
  getRequiredAttributeWithAlias() in AnnotationAttributes,
  AbstractAliasAwareAnnotationAttributeExtractor,
  MapAnnotationAttributeExtractor, MergedAnnotationAttributesProcessor
  in AnnotatedElementUtils, and postProcessAnnotationAttributes() in
  AnnotationUtils.

- Introduced numerous tests for implicit alias support, including
  AbstractAliasAwareAnnotationAttributeExtractorTestCase,
  DefaultAnnotationAttributeExtractorTests, and
  MapAnnotationAttributeExtractorTests.

- Updated Javadoc in @AliasFor regarding implicit aliases and in
  AnnotationUtils regarding "meta-present".

Issue: SPR-13345

SocketUtils is used to find available ports on localhost; however,
prior to this commit, SocketUtils incorrectly reported a port as
available on localhost if another process was already bound to
localhost on the given port but not to other network interfaces. In
other words, SocketUtils determined that a given port was available for
some interface though not necessarily for the loopback interface.

This commit addresses this issue by refactoring SocketUtils so that it
tests the loopback interface to ensure that the port is actually
available for localhost.

Issue: SPR-13321

Issue: SPR-13312

Issue: SPR-13312

This commit introduces an additional test case to ensure that explicit
local attribute aliases (configured via @AliasFor) do not accidentally
override attributes of the same names in meta-annotations (i.e., by
convention).

Issue: SPR-13325

Prior to this commit, attempting to synthesize an annotation from a map
of annotation attributes that contained nested maps instead of nested
annotations would result in an exception.

This commit addresses this issue by properly synthesizing nested maps
and nested arrays of maps into nested annotations and nested arrays of
annotations, respectively.

Issue: SPR-13338

It is a configuration error if an alias is declared via @AliasFor for
an attribute in a meta-annotation and the meta-annotation is not
meta-present. However, prior to this commit, the support for validating
the configuration of @AliasFor in AnnotationUtils currently silently
ignored such errors.

This commit fixes this by throwing an AnnotationConfigurationException
whenever a required meta-annotation is not present or meta-present on
an annotation that declares an explicit alias for an attribute in the
meta-annotation.

Issue: SPR-13335

Prior to this commit, an explicit override for an attribute in a
meta-annotation configured via @AliasFor could potentially result in an
incorrect override of an attribute of the same name but in the wrong
meta-annotation.

This commit fixes the algorithm in getAliasedAttributeName(Method,
Class) in AnnotationUtils by ensuring that an explicit attribute
override is only applied to the configured target meta-annotation
(i.e., configured via the 'annotation' attribute in @AliasFor).

Issue: SPR-13325

SPR-11512 introduced support for annotation attribute aliases via
@AliasFor, requiring the explicit declaration of the 'attribute'
attribute. However, for aliases within an annotation, this explicit
declaration is unnecessary.

This commit improves the readability of alias pairs declared within an
annotation by introducing a 'value' attribute in @AliasFor that is an
alias for the existing 'attribute' attribute. This allows annotations
such as @ContextConfiguration from the spring-test module to declare
aliases as follows.

public @interface ContextConfiguration {

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

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

    // ...
}

Issue: SPR-13289

Issue: SPR-13286

Issue: SPR-13067

Issue: SPR-13177

Issue: SPR-12938

Prior to this commit, Spring's MimeType checked for equality between
two MIME types based on the equality of their properties maps; however,
the properties maps contain string representations of the "charset"
values. Thus, "UTF-8" is never equal to "utf-8" which breaks the
contract for character set names which must be compared in a
case-insensitive manner.

This commit addresses this issue by ensuring that "charset" properties
in MimeType instances are compared as Java Charset instances, thereby
ignoring case when checking for equality between charset names.

Issue: SPR-13157

Issue: SPR-13146

This commit introduces a convenience method in AnnotationUtils for
synthesizing an annotation from its default attribute values.

TransactionalTestExecutionListener has been refactored to invoke this
new convenience method.

Issue: SPR-13087

This commit introduces support for automatically resolving a container
annotation configured via @Repeatable in AnnotationUtils'
getRepeatableAnnotations() and getDeclaredRepeatableAnnotations()
methods.

Issue: SPR-13068

This commit introduces a minor bug fix for getRepeatableAnnotations()
so that it fully complies with the contract of Java's
getAnnotationsByType() method with regard to repeatable annotations
declared on multiple superclasses.

Issue: SPR-13068

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