Rename header for "orig" destination

The UserDestinationMessageHandler adds a header providing a hint for
what the original destination a user may have used when subscribing.
That is then used when writing messages back to WebSocket clients to
ensure they dont see the internally used, transformed user destination.

This change moves the header name constatn to make it more broadly
applicable. For example SPR-11645.
Relax constraints in MessageHeaders for subclasses

Allow a subclass to modify MessageHeaders as well as override the
strategy for or even skip having `ID` and `TIMESTAMP` headers.

Issue: SPR-11468
Update MessageHeaders constructor

Following discussion with Gary.

Issue: SPR-11468
Merge pull request #509 from garyrussel/SPR-11468
Use unconstrained quotes in reference manual

Prior to this commit, there were numerous places in the reference
manual, where we would see output similar to the following:

    BeanDefinition`s with the `ApplicationContext

This commit addresses this issue by using unconstrained quotes
(e.g., ++XYZ++s) instead of backticks (e.g., `XYZ`s) when the formatted
text is immediately followed by an "s".

This commit also corrects a few typos and corrects natural English
pluralization of Java code elements in the reference manual where
appropriate -- for example, "@Controllers" becomes "@Controller classes,
etc.

Issue: SPR-11650
Clean up warnings that show up in Gradle build
Clean up warnings due to removal of legacy Jackson support
Introduce test for PropertySource + ACI in the TCF

This commit introduces an explicit integration test to verify that a
PropertySource can be set via a custom ApplicationContextInitializer in
the Spring TestContext Framework.

Issue: SPR-11666
Add JSR-107 cache annotations support

This commit adds support for the JSR-107 cache annotations alongside
the Spring's cache annotations, that is @CacheResult, @CachePut,
@CacheRemove and @CacheRemoveAll as well as related annotations
@CacheDefaults, @CacheKey and @CacheValue.

Spring's caching configuration infrastructure detects the presence of
the JSR-107 API and Spring's JCache implementation. Both
@EnableCaching and the cache namespace are able to configure the
required JCache infrastructure when necessary. Both proxy mode
and AspectJ mode are supported.

As JSR-107 permits the customization of the CacheResolver to use for
both regular and exception caches, JCacheConfigurer has been
introduced as an extension of CachingConfigurer and permits to define
those.

If an exception is cached and should be rethrown, it is cloned and
the call stack is rewritten so that it matches the calling thread each
time. If the exception cannot be cloned, the original exception is
returned.

Internally, the interceptors uses Spring's caching abstraction by default
with an adapter layer when a JSR-107 component needs to be called.
This is the case for CacheResolver and CacheKeyGenerator.

The implementation uses Spring's CacheManager abstraction behind the
scene. The standard annotations can therefore be used against any
CacheManager implementation.

Issue: SPR-9616
Use CacheResolver in Spring abstraction

Prior to this commit, the CacheResolver was not used by Spring's
caching abstraction. This commit provides the necessary configuration
options to tune how a cache is resolved for a given operation.

CacheResolver can be customized globally, at the operation level or at
the class level. This breaks the CachingConfigurer class and a support
implementation is provided that implements all methods so that the
default is taken if it's not overridden. The JSR-107 support has been
updated as well, with a similar support class.

In particular, the static and runtime information of a cache
operation were mixed which prevents any forms of caching. As the
CacheResolver and the KeyGenerator can be customized, every operation
call lead to a lookup in the context for the bean.

This commit adds CacheOperationMetadata, a static holder of all
the non-runtime metadata about a cache operation. This is used
as an input source for the existing CacheOperationContext.

Caching the operation metadata in an AspectJ aspect can have side
effects as the aspect is static instance for the current ClassLoader.
The metadata cache needs to be cleared when the context shutdowns.
This is essentially a test issue only as in practice each application
runs in its class loader. Tests are now closing the context properly
to honor the DisposableBean callback.

Issue: SPR-11490
polishing

This fixes a Java6 backward compatible issue introduced in the JCache
implementation.

This commit also adds new representative tests.

Issue: SPR-9616
fix CI build

Prior to this commit, AnnotatedJCacheableService contained an annotated
method demonstrating a failure scenario. This could break depending on
the order of the methods array as AopUtils creates the proxy if the
pointcut matches by checking each method.

On the CI server, the first method was this invalid use case so
checking if the proxy has to be created lead to an unexpected
exception. This scenario has been moved to its own private class now.
Don't encode '@' in {@code} tags
Don't encode '@' in {@code} tags
Update to JCache 1.0.0 final

Issue: SPR-11640
polishing

This commit fixes the handling of cached exceptions in the JSR-107
advisor. Such exceptions are now properly propagated instead of being
wrapped in a RuntimeException.

Issue: SPR-9616
Expand resource handling mechanism
Polishing Resource Handling

* documented some classes
* added a PrefixResourceResolver