See this document for more details:
    <https://github.com/jenkins-infra/documentation/blob/master/ci.adoc>

This may also address some issues we've been seeing in CI with file descriptor
leaks.

See jenkinsci/jenkins#2516

This reverts commit 1ce349a.

This reverts commit 113b984.

This reverts commit be71de8.

Update the Jenkinsfile to suitably run on ci.jenkins.io

findSubtypes uses ExtensionLists to determine derived classes.  This is
critcial to any operation that uses anything other than Java classes as
the required object type.  Also some required classes were not
loading/failing right away due to missing Jenkins.  The sort of
convoluted way to fix this was to introduce mocking.  Now, there's a
Jenkins "object" that is barebones enough to handle the necessary
methods to load the missing steps.

Add step

Build periodically

* Show display name of the plugin as h2
* Remove redundant h1
* Pass through cleaned up HTML instead of trying to convert
* Skip 'step' metastep
* Properly format unknown types

 [FIX WEBSITE-314] Formatting fixes

Update core to 2.263.3, args4j to 2.33

Resolves a maven warning and assures that we're using a consistent file
encoding no matter which platform is used for the build.

Has clearly stated nonNull return value

The javax.annotation.CheckForNull and javax.annotation.Nonnull have
been removed.

Replace the deprecated methods with current recommended methods.

The maven assembly plugin warns that it does not support directories.
The content of the zip file before this change is the same as the content
of the zip file after the change.

The dir directive generates a '*-bin' directory in the target.  That
directory is used for the file descriptor leak check in the Jenkinsfile.
It is more important to have the file leak detector checks than to remove
the maven warning.

This reverts commit 57a676c.

Update components

Match javax.servlet-api version in Jenkins core/pom.xml

Simplify this pom and retain plugin version consistency by using the
versions defined in the Jenkins plugin bom.

Use plugin bom

Bumps [bom-2.263.x](https://github.com/jenkinsci/pom) from 18 to 21.
- [Release notes](https://github.com/jenkinsci/pom/releases)
- [Changelog](https://github.com/jenkinsci/pom/blob/master/CHANGELOG.md)
- [Commits](https://github.com/jenkinsci/pom/commits)

Signed-off-by: dependabot[bot] <support@github.com>

…jenkins.tools.bom-bom-2.263.x-21

Bump bom-2.263.x from 18 to 21

Bumps [jenkins-core](https://github.com/jenkinsci/pom) from 2.277 to 2.278.
- [Release notes](https://github.com/jenkinsci/pom/releases)
- [Changelog](https://github.com/jenkinsci/pom/blob/master/CHANGELOG.md)
- [Commits](https://github.com/jenkinsci/pom/commits)

Signed-off-by: dependabot[bot] <support@github.com>

Bumps [bom-2.263.x](https://github.com/jenkinsci/pom) from 21 to 23.
- [Release notes](https://github.com/jenkinsci/pom/releases)
- [Changelog](https://github.com/jenkinsci/pom/blob/master/CHANGELOG.md)
- [Commits](https://github.com/jenkinsci/pom/commits)

Signed-off-by: dependabot[bot] <support@github.com>

…jenkins.tools.bom-bom-2.263.x-23

….jenkins-ci.main-jenkins-core-2.278