Make use of the new getAvailableExtensionNames() method.

Closes gh-23799

Upgrade to SLF4J 1.7.28, Groovy 2.5.8, RxJava 2.2.12, Joda-Time 2.10.4, Rome 1.12.2, OkHttp 3.14.3, Apache HttpClient 4.5.10, Apache Johnzon 1.1.13

Includes Netty 4.1.39 (aligned with Reactor) and Checkstyle 8.24.

Closes gh-23694

See also: 69214429 and eec183ef

This commit reverts all artifactory configuration changes in this
branch. A new build plan has been created for the master branch which is
tailored for the latest Gradle changes made on that branch.

Since gh-23282, our CI does not apply automatically the Artifactory
Gradle plugin during our build and we're now applying it "manually".
This commit backports this change since the build configuration is
shared between branches.

See gh-23282

Includes updated javadoc links for 5.1.x branch.

Fixes gh-23253

Includes Hibernate Validator 6.0.17 and renames "withoutJclOverSlf4j".

Includes upgrade to Reactor Californium SR9 proper.

Includes dependency management plugin 1.0.7.

Includes upgrade to Hibernate ORM 5.3.10 (for branch 5.1.x)

Closes gh-22693

See gh-22634

Closes gh-22522

This commit updates URLs to prefer the https protocol. Redirects are not followed to avoid accidentally expanding intentionally shortened URLs (i.e. if using a URL shortener).

# Fixed URLs

## Fixed But Review Recommended
These URLs were fixed, but the https status was not OK. However, the https status was the same as the http request or http redirected to an https URL, so they were migrated. Your review is recommended.

* http://quartz-scheduler.org/api/2.2.1/ (301) migrated to:
  https://www.quartz-scheduler.org/api/2.2.1/ ([https](https://quartz-scheduler.org/api/2.2.1/) result 404).

## Fixed Success
These URLs were fixed successfully.

* http://docs.jboss.org/jbossas/javadoc/4.0.5/connector/ migrated to:
  https://docs.jboss.org/jbossas/javadoc/4.0.5/connector/ ([https](https://docs.jboss.org/jbossas/javadoc/4.0.5/connector/) result 200).
* http://docs.jboss.org/jbossas/javadoc/7.1.2.Final/ migrated to:
  https://docs.jboss.org/jbossas/javadoc/7.1.2.Final/ ([https](https://docs.jboss.org/jbossas/javadoc/7.1.2.Final/) result 200).
* http://docs.oracle.com/cd/E13222_01/wls/docs90/javadocs/ migrated to:
  https://docs.oracle.com/cd/E13222_01/wls/docs90/javadocs/ ([https](https://docs.oracle.com/cd/E13222_01/wls/docs90/javadocs/) result 200).
* http://docs.oracle.com/javaee/7/api/ migrated to:
  https://docs.oracle.com/javaee/7/api/ ([https](https://docs.oracle.com/javaee/7/api/) result 200).
* http://docs.oracle.com/javase/8/docs/api/ migrated to:
  https://docs.oracle.com/javase/8/docs/api/ ([https](https://docs.oracle.com/javase/8/docs/api/) result 200).
* http://fasterxml.github.io/jackson-core/javadoc/2.9/ migrated to:
  https://fasterxml.github.io/jackson-core/javadoc/2.9/ ([https](https://fasterxml.github.io/jackson-core/javadoc/2.9/) result 200).
* http://fasterxml.github.io/jackson-databind/javadoc/2.9/ migrated to:
  https://fasterxml.github.io/jackson-databind/javadoc/2.9/ ([https](https://fasterxml.github.io/jackson-databind/javadoc/2.9/) result 200).
* http://fasterxml.github.io/jackson-dataformat-xml/javadoc/2.9/ migrated to:
  https://fasterxml.github.io/jackson-dataformat-xml/javadoc/2.9/ ([https](https://fasterxml.github.io/jackson-dataformat-xml/javadoc/2.9/) result 200).
* http://hc.apache.org/httpcomponents-client-ga/httpclient/apidocs/ migrated to:
  https://hc.apache.org/httpcomponents-client-ga/httpclient/apidocs/ ([https](https://hc.apache.org/httpcomponents-client-ga/httpclient/apidocs/) result 200).
* http://issues.gradle.org/browse/GRADLE-1116 migrated to:
  https://issues.gradle.org/browse/GRADLE-1116 ([https](https://issues.gradle.org/browse/GRADLE-1116) result 200).
* http://projectreactor.io/docs/core/release/api/ migrated to:
  https://projectreactor.io/docs/core/release/api/ ([https](https://projectreactor.io/docs/core/release/api/) result 200).
* http://tiles.apache.org/framework/apidocs/ migrated to:
  https://tiles.apache.org/framework/apidocs/ ([https](https://tiles.apache.org/framework/apidocs/) result 200).
* http://tiles.apache.org/tiles-request/apidocs/ migrated to:
  https://tiles.apache.org/tiles-request/apidocs/ ([https](https://tiles.apache.org/tiles-request/apidocs/) result 200).
* http://www.apache.org/licenses/LICENSE-2.0 migrated to:
  https://www.apache.org/licenses/LICENSE-2.0 ([https](https://www.apache.org/licenses/LICENSE-2.0) result 200).
* http://www.eclipse.org/aspectj/doc/released/aspectj5rt-api/ migrated to:
  https://www.eclipse.org/aspectj/doc/released/aspectj5rt-api/ ([https](https://www.eclipse.org/aspectj/doc/released/aspectj5rt-api/) result 200).
* http://www.reactive-streams.org/reactive-streams-1.0.1-javadoc/ migrated to:
  https://www.reactive-streams.org/reactive-streams-1.0.1-javadoc/ ([https](https://www.reactive-streams.org/reactive-streams-1.0.1-javadoc/) result 200).
* http://docs.spring.io/spring-framework/docs migrated to:
  https://docs.spring.io/spring-framework/docs ([https](https://docs.spring.io/spring-framework/docs) result 301).
* http://glassfish.java.net/nonav/docs/v3/api/ migrated to:
  https://glassfish.java.net/nonav/docs/v3/api/ ([https](https://glassfish.java.net/nonav/docs/v3/api/) result 301).
* http://pic.dhe.ibm.com/infocenter/wasinfo/v7r0/topic/com.ibm.websphere.javadoc.doc/web/apidocs/ migrated to:
  https://pic.dhe.ibm.com/infocenter/wasinfo/v7r0/topic/com.ibm.websphere.javadoc.doc/web/apidocs/ ([https](https://pic.dhe.ibm.com/infocenter/wasinfo/v7r0/topic/com.ibm.websphere.javadoc.doc/web/apidocs/) result 301).
* http://projects.spring.io/spring-framework migrated to:
  https://projects.spring.io/spring-framework ([https](https://projects.spring.io/spring-framework) result 301).
* http://springframework.org/schema migrated to:
  https://springframework.org/schema ([https](https://springframework.org/schema) result 301).
* http://ehcache.org/apidocs/2.10.4 (301) migrated to:
  https://www.ehcache.org/apidocs/2.10.4 ([https](https://ehcache.org/apidocs/2.10.4) result 301).

Includes Mockito 2.25, Undertow 2.0.19, OpenPDF 1.2.10, JRuby 9.2.6.