Issue: SPR-13513

Issue: SPR-13514

SpringJUnit4ClassRunner, SpringClassRule, and SpringMethodRule now
throw an IllegalStateException with a meaningful message if JUnit 4.9
is not present in the classpath (specifically if
org.junit.runners.model.MultipleFailureException cannot be loaded).

Issue: SPR-13521

This commit adds support for origins with a trailing slash or a path,
in order to avoid printing a stacktrace in the logs when
WebUtils#isSameOrigin(HttpRequest) parses such invalid Origin header
value.

Issue: SPR-13478

This is in preparation for a migration from JUnit 3 to JUnit 4.

Issue: SPR-13514, SPR-13515

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

This commit introduces a new ScriptRenderException in order to:
 - Print in the resulting error page the reason of the script failure
 - Not print the whole stacktrace in the logs

The ScriptRenderException thrown in ScriptTemplateView#renderMergedOutputModel()
is wrapped into a ServletException in order to avoid printing 2 times the messages in
the logs (throwing directly a ScriptRenderException would make it wrapped in a
NestedServletException that contains a getMessage() override not needed in this
context)

Issue: SPR-13488

ResponseBodyEmitter now registers by default to receive callbacks
on timeout/completion and sets its internal "complete" flag to true
in order to prevent proactively further use of the emitter.

Issue: SPR-13498

Issue: SPR-13509

Issue: SPR-13493
Issue: SPR-13123
Issue: SPR-12503

Issue: SPR-13504

Issue: SPR-13366

Issue: SPR-13439

Prior to this commit, HttpEntityMethodProcessor would process
conditional requests even if those aren't GET requests.
This is an issue for POST requests with "If-None-Match: *" headers and
many other use cases, which should not receive an HTTP 304 Not Modified
status in response.

This commit only triggers ETag/Last-Modified conditional requests bits
for GET requests.

Issue: SPR-13496

Issue: SPR-13492

Issue: SPR-13494

As of Undertow 1.3.0, several APIs have been changed: replacing Xnio's
Pool/Pooled references to Undertow's new ByteBufferPool abstraction.
This move has been made, as part of
https://issues.jboss.org/browse/UNDERTOW-522, to prepare deprecations in
the Xnio API.

This commit adds a new strategy to deal with both 1.0-1.2 and 1.3
Undertow generations.

Issue: SPR-13366

Issue: SPR-9456

The MockHttpServletRequestBuilder now uses java.net.URI internally
rather than UriComponents.

This means that for the MockMvcRequestBuilders method variants that
accept a java.net.URI we can use it as is. The difference is almost
none but it does mean that you can create a URI with double slashes
(for testing purposes) and have it remain that way.

Issue: SPR-13435

Issue: SPR-13479

Some converters (Jackson, Gson, Protobuf) already do this. It is now
also done in AbstractMessageConverterMethodArgumentResolver which
enforces a consistent behavior across controller method arguments.

Issue: SPR-12745

Issue: SPR-13416

Issue: SPR-7794

Also revised StandardScriptFactory for finer-grained template methods, added further configuration variants to StandardScriptEvaluator, and identified thread-local ScriptEngine instances in ScriptTemplateView by appropriate key.

Issue: SPR-13491
Issue: SPR-13487

This commit makes ThreadLocal<ScriptEngine> engineHolder ScriptTemplateView
field static in order to limit the maximum number of ScriptEngine instances
to the number of threads, regardless of the number of view instances.

Issue: SPR-13487

This commit introduces ignored, failing tests that demonstrate that the
@cache* annotations are not yet supported as merged composed annotations.

Issue: SPR-13475

* SPR-13468:
  Support @CrossOrigin as a merged composed annotation