Issue: SPR-7549

Includes optimized method/header resolution in CorsConfiguration.

Issue: SPR-14617

Prior to this commit, extracting an HTTP response with an empty body
and no Content-Type header using the WebClient would:

* trigger the use of the Jackson2JsonDecoder
* throw a NoSuchElementException because of the use of `Flux.single()`

This commit changes this behavior to `Flux.singleOrEmpty()` to avoid
throwing exceptions for empty Flux instances.

Issue: SPR-14582

Issue: SPR-14607

Issue: SPR-14616

Default ClientOptions enable SSL support.

Issue: SPR-14593

* reactor-core 3.0.1.BUILD-SNAPSHOT
* reactor-netty 0.6.0.BUILD-SNAPSHOT

This commit ensures that JUnit XML reports are generated in the old
Gradle 2.x location for all tests in the spring-test module.

Issue: SPR-14569

Issue: SPR-14569

Since the upgrade to Gradle 3, our Bamboo build is failing because it
can't find test reports "at the usual location".

This commit restores the location that Gradle 2 was using until we
upgrade to a version of Bamboo that supports it.

Issue: SPR-14569

Fix the build to work with reactor-core-3.0.0.RELEASE

Previously the IDE (STS) was resolving a different reactor-core
version (3.0.0.BUILD-SNAPSHOT) than the build (3.0.0.RELEASE). This
discrepancy was due to the fact that reactor-netty now brings in
reactor-core 3.0.0.RELEASE. Gradle's version conflict resolution is to use
the latest version. However, the optional dependency on reactor-core
3.0.0.BUILD-SNAPSHOT was making the build path of the IDE use the SNAPSHOT.

This fix leverages a resolutionStrategy to ensure a consistent version of
reactor-core is used throughout the entire project. It also bumps up the
reactor-core version to 3.0.0.RELEASE to be consistent with reactor-netty.
Care is taken to only change 3.x vesion since 2.x is still used within
the codebase.

Issue: SPR-14594

Issue: SPR-14600

(cherry picked from commit 5222489a)

Issue: SPR-14599

Issue: SPR-14599

Issue: SPR-14585
(cherry picked from commit da567580)

Issue: SPR-14598
(cherry picked from commit 188e5327)

(cherry picked from commit 1932a9d7)

This commit adds a setter for the default persistence unit's
defaultPersistenceUnitRootLocation attribute.

Issue: SPR-14595

Issue: SPR-14580

Issue: SPR-14585

Issue: SPR-14585

Issue: SPR-11217

Since we have a dedicated section regarding Ehcache that is only
applicable to Ehcache 2.x, this commit clarifies that Ehcache 3.x is
JSR-107 compliant and the JCache support should be used with it
rather than attempting to configure the Ehcache 2.x support.

Commit 240f254b has introduced support for `java.util.Optional` in the
cache abstraction. If such type is present, the contained value is cached
if it is present.

This new feature slightly changed the semantic of `#result` that was
documented up till this commit as the "return value of the method
invocation". This is no longer true as `#result` for `Optional<T>`
refers to the `T` instance and not the `Optional` instance.

This commit clarifies both the javadoc and the documentation.

Issue: SPR-14587

* pr/1132:
  Add aditional example to CronSequenceGenerator

CronSequenceGenerator supports comma separated expressions but does not
provide an example for it. This commit adds such an example.

Closes gh-1132

Issue: SPR-14569

Previously invoking HtmlUnitRequestBuilder merge caused the pathInfo of
the parent to be corrupted. This could additional invocations with the
same parent.

This fix ensures that the parent is no longer directly used. Instead,
we create a copy of the parent by merging the parent that was passed in
with the copy.

Fixes SPR-14584

(cherry picked from commit a4a71a89)

Issue: SPR-14551