Prior to this commit, SpringJUnit4ConcurrencyTests was broken due to
recent additions of test methods in SampleTests.

This commit fixes the broken test by removing hard coded constants and
replacing them with dynamic lookups for JUnit 4 @test methods.

Issue: SPR-15130

Issue: SPR-15160

Dropping GenericCollectionTypeResolver in favor of direct ResolvableType usage.

Issue: SPR-15160

Issue: SPR-15182

Issue: SPR-15180

Issue: SPR-15179

Issue: SPR-15178

Issue: SPR-14550

Issue: SPR-15159

Issue: SPR-14602

Issue: SPR-14505

Issue: SPR-15175

Issue: SPR-15146

Issue: SPR-15168

* pr/1294:
  Fix Javadoc for CronSequenceGenerator

Closes gh-1294

* pr/1279:
  Polish contribution
  Update logging documentation to include Log4j 2

Since Log4J 1.x is EOL there is no need to have a dedicated section for
it.

Closes gh-1279
Issue: SPR-15170

This also updates the version numbers provided in the sample pom.xml
snippets for configuring logging for SLF4J and Log4j 1.x. A sample
log4j2.xml file is also given with the same configuration as
demonstrated in the log4j.properties example. The link to the Log4j 1.x
site has been fixed to point to the 1.2 URL (do note that Log4j 1.2 is
end of life and is not compatible with JDK 9+).

See gh-1279

A bogus pre-release of Kotlin 1.1.0-beta-17 seems to be
in Spring Artifactory cache, this change make Gradle using
the right one from Bintray. Using --refresh-dependencies
may be needed to pick-up the right one.

Previously, the dependency management and propdeps-maven plugins
were being applied to all projects. The latter caused a problem with
publishing to Artifactory as the buildSrc project now had the
propdeps-maven plugin applied to it.

This commit removes the logic that was applying the propdeps-plugin
to all projects so that it's only applied to subprojects excluding
the buildSrc project. The logic that applies the dependency management
plugin has been moved to the same location. It is applied after the
propdeps-maven plugin as, otherwise, the pom customization does not
work correctly and optional dependencies are not included in
generated poms.

Issue: SPR-15167

Issue: SPR-15167

See RFC 7807: Problem Details for HTTP APIs

* application/problem+json
* application/problem+xml

Issue: SPR-15110

Spring Framework 5.0 now requires Kotlin 1.1+. This commit
also re-enable Kotlin JSR 223 unit tests.

Issue: SPR-15100

This commit maps the UnsupportedMediaTypeException, used by both client
and server, to a server-side UnsupportedMediaTypeStatusException in the
functional web framework.

This commit adds the FormHttpMessageReader and FormHttpMessageWriter to
the server and client default configuration respectively.

Prior to this commit, the org.springframework.tests.Assume class could
fail to load resulting in a NoClassDefFoundError if parsing of the
'testGroups' system property failed. This is because the parsing took
place while initializing a static field.

This commit addresses this issue by moving the 'testGroups' system
property lookup to a dedicated method that is lazily invoked upon
demand instead of eagerly when loading the Assume class itself.

In addition, when an error occurs, TestGroup.parse() now logs the
complete original value of the supplied test groups string instead of
potentially omitting the "all-" prefix. This results in more
informative error messages similar to the following.

  java.lang.IllegalStateException: Failed to parse 'testGroups' system
  property: Unable to find test group 'bogus' when parsing testGroups
  value: 'all-bogus'. Available groups include:
  [LONG_RUNNING,PERFORMANCE,JMXMP,CI]

Issue: SPR-15163

The generic encode method in UriUtils that encodes any character
outside the reserved character set for a URI is meant for "strict"
encoding of URI variable values. This commit adds a couple more
conveninence methods that accept a Map or array of URI variable
values to encode.

This facilitates the use case where the URI template is assumed to
be encoded while URI variables are encoded strictly to avoid any
possibility for unwanted reserved characters:

Map<String, ?> encodedUriVars = UriUtils.encodeUriVariables(uriVars);
uriComponentsBuilder.build(true).expand(encodedUriVars).toUri();

Issue: SPR-14970

Issue: SPR-14828

Issue: SPR-15134

Issue: SPR-15074