* Fix intermittently failing tests, mostly increasing timeout

Fix several unit tests that are intermittently failing. All fixes
involve increasing timeouts. Adjusted formatting in several areas within
updated tests.

* Remove formatting/refactoring from previous commit

Superfluous formatting and refactoring was making review impossible.

Add JavadocMethod and MissingJavadocMethod checks to Checkstyle.
Checks ensure there are no missing Javadoc comments for public methods,
 and that each of the Javadoc comments describe all method parameters.

Add suppressions.xml Checkstyle configuration file to exclude Jmh, Test,
and Internal from MissingJavadocMethod check.

Move Checkstyle configuration files and License headers into config directory.

Fix Javadoc comments that violate the added checks.

* Bump gradle to 6.8.3

* Modify root build.gradle

* Create and validate standardized java source header

Update Checkstyle to validate all java source files have a standard
header. Remove FixLiscenseHeaders.java unit test as it duplicates
Checkstyle functionality. Standard header is block java comment, instead
of dangling Javadoc comment. Create standard header template
(HEADER_JAVA) in project root. Reference header template in
build.gradle. Update CONTRIBUTING.md to exact text of header template.

* Convert Licenses from dangling Javadoc to block comment

Standardize License based off of HEADER_JAVA file. All headers are block
Java comments.

* Restoring FixLicenseHeaders.java and updating CONTRIBUTING date

* Updated License dates to 2016

Several files had 2017 dates for License. Checkstyle now specifically
looks for 2016 date in License comments.

* Fix bad logic for header check in FixLicenseHeaders test

Bumps build-info-extractor-gradle from 4.20.0 to 4.21.0.
Signed-off-by: Ndependabot-preview[bot] <support@dependabot.com>
Co-authored-by: Ndependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

* #7195 Allow zip result to be garbage collected

* Also `null` collected values on error and complete

* Update MaybeZipArray.java

* Update SingleZipArray.java

* Update MaybeZipArray.java

* Update SingleZipArray.java

* Update MaybeZipArray.java

* Update MaybeZipArray.java
Co-authored-by: NAlex <alex@xenonlightz.de>
Co-authored-by: NDavid Karnok <akarnokd@gmail.com>

Bumps [mockito-core](https://github.com/mockito/mockito) from 3.7.7 to 3.8.0.
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](https://github.com/mockito/mockito/compare/v3.7.7...v3.8.0)
Signed-off-by: Ndependabot-preview[bot] <support@dependabot.com>
Co-authored-by: Ndependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Bumps [biz.aQute.bnd.gradle](https://github.com/bndtools/bnd) from 5.2.0 to 5.3.0.
- [Release notes](https://github.com/bndtools/bnd/releases)
- [Changelog](https://github.com/bndtools/bnd/blob/master/docs/ADDING_RELEASE_DOCS.md)
- [Commits](https://github.com/bndtools/bnd/commits)
Signed-off-by: Ndependabot-preview[bot] <support@dependabot.com>
Co-authored-by: Ndependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Bumps gradle-animalsniffer-plugin from 1.5.2 to 1.5.3.
Signed-off-by: Ndependabot-preview[bot] <support@dependabot.com>
Co-authored-by: Ndependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Bumps jmh-gradle-plugin from 0.5.2 to 0.5.3.
Signed-off-by: Ndependabot-preview[bot] <support@dependabot.com>
Co-authored-by: Ndependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Bumps [junit](https://github.com/junit-team/junit4) from 4.13.1 to 4.13.2.
- [Release notes](https://github.com/junit-team/junit4/releases)
- [Changelog](https://github.com/junit-team/junit4/blob/main/doc/ReleaseNotes4.13.1.md)
- [Commits](https://github.com/junit-team/junit4/compare/r4.13.1...r4.13.2)
Signed-off-by: Ndependabot-preview[bot] <support@dependabot.com>
Co-authored-by: Ndependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Bumps [gradle-maven-publish-plugin](https://github.com/vanniktech/gradle-maven-publish-plugin) from 0.14.1 to 0.14.2.
- [Release notes](https://github.com/vanniktech/gradle-maven-publish-plugin/releases)
- [Changelog](https://github.com/vanniktech/gradle-maven-publish-plugin/blob/master/CHANGELOG.md)
- [Commits](https://github.com/vanniktech/gradle-maven-publish-plugin/compare/0.14.1...0.14.2)
Signed-off-by: Ndependabot-preview[bot] <support@dependabot.com>
Co-authored-by: Ndependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Bumps [gradle-maven-publish-plugin](https://github.com/vanniktech/gradle-maven-publish-plugin) from 0.13.0 to 0.14.1.
- [Release notes](https://github.com/vanniktech/gradle-maven-publish-plugin/releases)
- [Changelog](https://github.com/vanniktech/gradle-maven-publish-plugin/blob/master/CHANGELOG.md)
- [Commits](https://github.com/vanniktech/gradle-maven-publish-plugin/compare/0.13.0...0.14.1)
Signed-off-by: Ndependabot-preview[bot] <support@dependabot.com>
Co-authored-by: Ndependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

* 3.x: Release to Sonatype directly

* Update build.gradle

* Update gradle.properties

* Turn RS into compile dependency in POM

* Fix the POM of the snapshot/artifactory upload

Co-authored-by: NWayne_Yang <wayne_yang@perfectcorp.com>

Bumps build-info-extractor-gradle from 4.19.0 to 4.20.0.
Signed-off-by: Ndependabot-preview[bot] <support@dependabot.com>
Co-authored-by: Ndependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Issue-Id: #7154
Co-authored-by: NSergej Isbrecht <sergej.isbrecht@gmail.com>

* Support for scheduled release of threads in Io Scheduler

* Test for rx3.io-scheduled-release

* Fix tests, addressed Javadoc feedback

Bumps build-info-extractor-gradle from 4.18.3 to 4.19.0.
Signed-off-by: Ndependabot-preview[bot] <support@dependabot.com>
Co-authored-by: Ndependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

* 3.x: onReduceBackpressure internals cleanup

* Update FlowableOnBackpressureReduceTest.java

* Update FlowableOnBackpressureReduceWithTest.java

Bumps [mockito-core](https://github.com/mockito/mockito) from 3.7.0 to 3.7.7.
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](https://github.com/mockito/mockito/compare/v3.7.0...v3.7.7)
Signed-off-by: Ndependabot-preview[bot] <support@dependabot.com>
Co-authored-by: Ndependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>