Restore the ability to create a TypeDescriptor for a collection or
map where the generics may be null.

Issue: SPR-11006

Refactor TypeDescriptor to use ResolvableType in order to retain full
generic type information, in the process fixing MultiValueMap support
in MapToMapConverter.

Issue: SPR-9499

Comprehensive update to the framework's TimeZone handling, including a new TimeZoneAwareLocaleContext and a LocaleContextResolver for Spring MVC

A few noteworthy minor changes: LocaleContext.getLocale() may return null in special cases (not by default), which our own accessing classes are able to handle now. If there is a non-null TimeZone user setting, we're exposing it to all collaborating libraries, in particular to JSTL, Velocity and JasperReports. Our JSR-310 and Joda-Time support falls back to checking the general LocaleContext TimeZone now, adapting it to their time zone types, if no more specific setting has been provided. Our DefaultConversionService has TimeZone<->ZoneId converters registered. And finally, we're using a custom parseTimeZoneString method now that doesn't accept the TimeZone.getTimeZone(String) GMT fallback for an invalid time zone id anymore.

Issue: SPR-1528

Issue: SPR-1528

Issue: SPR-10631

Add ByteBufferConverter that is registered by default with the
DefaultConversionService. Allows conversion from/to a ByteBuffer and
byte[] or to any type that can be converted via a byte[].

Issue: SPR-10712

Issue: SPR-10130

Update StringToEnumConverterFactory to search superclasses until
Class.isEnum() returns true. This allows conversion when the
enum class is obtained from the enum value:

    public static enum SubFoo {
        BAR { String s() { return "x"; } };
        abstract String s();
    }

    conversionService.convert("BAR", SubFoo.BAR.getClass())

This fix is particularly important when converting collections of
enums.

Issue: SPR-10329

- fix @since version in array()
- format method-level Javadoc
- unescape HTML-escaped angle brackets with {@code} blocks

Add a static factory method that can be used to create an array
TypeDescriptor with a specific element type. Allows array types
with generic elements to be constructed.

Issue: SPR-9792

This reverts commit 45fa5082, reversing
changes made to a312d900.

Issue: SPR-10130

Issue: SPR-10128

Issue: SPR-10127

Previously the algorithm used by GenericConversionService to find
converters incorrectly searched for interfaces working up from the
base class. This caused particular problems with custom List
converters as as the Collection interface would be considered before
the List interface giving CollectionToObjectConverter precedence
over the custom converter.

The updated algorithm restores the class search order to behave in the
same way as Spring 3.1.

Issue: SPR-10116
Backport-Issue: SPR-10117
Backport-Commit: aa914497

Previously the algorithm used by GenericConversionService to find
converters incorrectly searched for interfaces working up from the
base class. This caused particular problems with custom List
converters as as the Collection interface would be considered before
the List interface giving CollectionToObjectConverter precedence
over the custom converter.

The updated algorithm restores the class search order to behave in the
same way as Spring 3.1.

Issue: SPR-10116

In particular, avoiding synchronized Sets and Maps wherever possible (preferring a ConcurrentHashMap even instead of a synchronized Set) and specifying appropriate ConcurrentHashMap initial capacities (even if we end up choosing 16).

 - Support external Javadoc links using Gradle's javadoc.options.links

 - Fix all other Javadoc warnings, such as typos, references to
   non-existent (or no longer existent) types and members, etc,
   including changes related to the Quartz 2.0 upgrade (SPR-8275) and
   adding the HTTP PATCH method (SPR-7985).

 - Suppress all output for project-level `javadoc` tasks in order to
   hide false-negative warnings about cross-module @see and @link
   references (e.g. spring-core having a @see reference to spring-web).
   Use the `--info` (-i) flag to gradle at any time to see project-level
   javadoc warnings without running the entire `api` task. e.g.
   `gradle :spring-core:javadoc -i`

 - Favor root project level `api` task for detection of legitimate
   Javadoc warnings. There are now zero Javadoc warnings across the
   entirety of spring-framework. Goal: keep it that way.

 - Remove all @link and @see references to types and members that exist
   only in Servlet <= 2.5 and Hibernate <= 4.0, favoring 3.0+ and 4.0+
   respectively. This is necessary because only one version of each of
   these dependencies can be present on the global `api` javadoc task's
   classpath. To that end, the `api` task classpath has now been
   customized to ensure that the Servlet 3 API and Hibernate Core 4 jars
   have precedence.

 - SPR-8896 replaced our dependency on aspectjrt with a dependency on
   aspectjweaver, which is fine from a POM point of view, but causes
   a spurious warning to be emitted from the ant iajc task that it
   "cannot find aspectjrt on the classpath" - even though aspectjweaver
   is perfectly sufficient. In the name of keeping the console quiet, a
   new `rt` configuration has been added, and aspectjrt added as a
   dependency to it. In turn, configurations.rt.asPath is appended to
   the iajc classpath during both compileJava and compileTestJava for
   spring-aspects.

Issue: SPR-10078, SPR-8275, SPR-7985, SPR-8896

Annotations are no longer resolved in the constructor and are cached
for improved performance.

Issue: SPR-9166

Remove canBypassConvert() methods from the ConversionService SPI
interface, restoring it to the previous Spring 3.1 incarnation.

Bypassing conversion is now only supported when using a
GenericConversionService.

Issue: SPR-9566

Bypass ObjectToObject conversion when source and object types are
identical and protect against a null source object.

Prior to this commit the TypeDescriptor was used to determine if
conversion was necessary.  This caused issues when comparing a
descriptor with annotations to one without.  The updated code
now compares using TypeDescriptor.getType().

The ObjectToObject converter will now no longer attempt to convert
null source objects.

Issue: SPR-9933

TypeDescriptor.valueOf now uses GenericCollectionTypeResolver to resolve
Collection and Map element types whereas previously this information was
simply not supported, i.e. null.

Issue: SPR-9257

Content:

 - Rename Conditional{Conversion=>Converter}
 - Add @since tags where appropriate
 - Update Apache date headers to read 2002-2012 (not just 2012)
 - Correct minor Javadoc typo

Style:

 - Polish line breaks / whitespace
 - Use wildcard static imports where appropriate

Issue: SPR-9566, SPR-9692, SPR-9928, SPR-9927

EnumToStringConverter in now conditional and only matches Enums that
do not implement interfaces that can be converted.

Issue: SPR-9692

Prior to this commit conversion between like types would often result in
a copy of the object. This can be problematic in the case of large byte
arrays and objects that do not have a default constructor.

The ConversionService SPI now includes canBypassConvert methods that can
be used to deduce when conversion is not needed. Several existing
converters have been updated to ensure they only apply when source and
target types differ.

This change introduces new methods to the ConversionService that will
break existing implementations. However, it anticipated that most users
are consuming the ConversionService interface rather then extending it.

Issue: SPR-9566

Introduce new ConditionalConversion interface that can be applied to
Converter, ConverterFactory or GenericConverter interfaces to make
them conditional. Prior to this commit the only
ConditionalGenericConverter could be conditional.

Issue: SPR-9928

Refactor internal workings of GenericConversionService in order to
better support future enhancements. This commit should not affect
existing behavior.

Issue: SPR-9927

Conversion to and from UUID objects is now supported by the
DefaultConversionService.

Issue: SPR-9765

default constructor (as long as a new map copy is not required).

Issue: SPR-9284

- Use generic typing for getAnnotation()
- Add hasAnnoation() method
- Update existing code and tests to make use of changes

Issue: SPR-9744