This commit fixes an old bug in ModelAndViewContainer where getModel
returns a new ModelMap instance that isn't saved and re-used.

Issue: SPR-14045

The DeferredResult~ and the ResponseBodyEmitterReturnValueHandler now
each expose an adapter mechanism for plugging in other async return
value types. As a result the ListenableFutureReturnValueHandler and
CompletionStageReturnValueHandler are no longer needed and are now
deprecated.

Issue: SPR-14046

Issue: SPR-14048

Issue: SPR-14030

Consistent lazy resolution of default executor/scheduler for Async/ScheduledAnnotationBeanPostProcessor

Issue: SPR-14030

Support a limited set of *Aware interfaces for TypeFilters created
via the @ComponentScan annotation.

Issue: SPR-14009

* SPR-13998:
  Polish ContextCustomizer support in the TCF
  Introduce ContextCustomizer API in the TestContext Framework

Issue: SPR-13998

Allow third-parties to contribute ContextCustomizers that can customize
ApplicationContexts created by the Spring TestContext Framework (TCF)
before they are refreshed.

A customizer may be provided via a ContextCustomizerFactory which is
registered with `spring.factories`. Each factory is consulted whenever
a new ApplicationContext needs to be created by the TCF. Factories may
inspect various details about the test and either return a new
ContextCustomizer or null.

ContextCustomizers are similar to ApplicationContextInitializers and
may perform any number of tasks, including bean registration, setting
of active profiles, etc.

Issue: SPR-13998

Issue: SPR-14037

Issue: SPR-14010

Issue: SPR-14025

Issue: SPR-14028

Issue: SPR-14003

Issue: SPR-14007

ConstructorResolver exposes parameter signature from user-declared class (in case of a CGLIB-generated subclass)

Issue: SPR-14015

Issue: SPR-13968

The MultiServerUserRegistry now supports scenarios where the same user
is connected to multiple servers. For such cases the SimpUser returned
from the registry exposes all sessions across all servers.

Issue: SPR-13800

Issue: SPR-13800

* SPR-14035:
  Polish ServletTestExecutionListener[Tests]
  Support servlet listener activate attribute

Add a ServletTestExecutionListener.ACTIVATE_LISTENER attribute which
can be set on the TestContext to trigger activation of the listener
even if a `@WebAppConfiguration` is not present.

Issue: SPR-14035

This commit adds a new "validator" XML attribute to the
`<websocket:message-broker/>` element. This allows configuring a
specific Validator to be used for payload validation.

Issue: SPR-13996

Previously, the generic type of a simple pojo event implementing
ResolvableTypeProvider wasn't detected properly. This commit fixes the
logic when the generic type is not provided to reuse what
PayloadApplicationEvent is already doing anyway.

Issue: SPR-14029

* pr/992:
  Fix typo

Closes gh-992

Prior to this commit, the @ContextConfiguration annotation was required
to be present even if default XML files, Groovy scripts, or
@Configuration classes were detected; however, in such cases the
@ContextConfiguration was typically declared empty and therefore
seemingly unnecessary boilerplate.

This commit permits @ContextConfiguration to be omitted whenever it can
be reasonably deduced. Consequently, integration tests such as the
following are now supported.

    @RunWith(SpringRunner.class)
    public class MyTest {

        @Autowired String myBean;

        @test public void example() { /* ... */ }

        @Configuration
        static class Config {

            @Bean String myBean() {
                return "Hello";
            }
        }
    }

Issue: SPR-13955

Prior to this commit, the springUrl Velocity macro would only prepend
the context to the given URL; this means that the
ServletHttpResponse.encodeUri method is not called and neither the
ResourceUrlProvider.

This commit changes this macro to use RequestContext.getContextUrl which
prepends the context and encodes the URI.

Issue: SPR-14027

* philwebb-testcontext:
  Polishing
  Remove @BootstrapWith from @WebAppConfiguration

Update @WebAppConfiguration so that it no longer directly specifies
a TestContextBootstrapper. This allows third parties to use the
annotation in combination with their own bootstrapper.

BootstrapUtils now provides the detection logic for when
WebTestContextBootstrapper should be used.

Issue: SPR-13991

Issue: SPR-13972

Issue: SPR-13992

Issue: SPR-13992

Issue: SPR-13992