[JENKINS-59849] Don't fail to serve resource files with nontrivial names

Resolve RunListener TODO using Functions#isExtensionsAvailable

Contributing guidelines: Update the Java versions documentation

[JENKINS-59800] - Add line-height CSS property to fix the "Create Administrator Account" view headlines

* add one Spotbugs exclude and replaced Nonnull with CheckForNull because assigned variables have CheckForNull annotations

* Update core/src/main/java/jenkins/security/NonSerializableSecurityContext.java
Co-Authored-By: NEvaristo Gutiérrez <egutierrez@cloudbees.com>

Modernize LoginRedirectTest

[JENKINS-36720] - Spotbugs fix CO_COMPARETO_INCORRECT_FLOATING

simplified assertions and removed unthrown exceptions

Add Polish translations

Contributing guidelines: Skip SpotBugs instead of Findbugs for quick build

Co-Authored-By: NDaniel Beck <1831569+daniel-beck@users.noreply.github.com>

Resolve TODO using JenkinsRule#waitOnline

The mentioned ticket JENKINS-33377 has been resolved.
Therefore `isExtensionsAvailable` now also checks that Jenkins is not terminating.

Replace deprecated `HudsonTestCase` and add URL path assertions.

[JENKINS-59684] Support "alert-info" for admin monitor in popup

[JENKINS-59605] Unify the JS validation behavior and the AJAX one

IntelliJ/Java: Duplicate code -> ChunkedInputStream.advanceChunk

[JENKINS-48375] - Make Atom the default feed type in UI and the response application type (Former RSS feeds use Atom)

* replaced static test classes with mocks

* added CALLS_REAL_METHODS as defaultAnswer

* Update core/src/test/java/hudson/slaves/NodeListTest.java
Co-Authored-By: NTim Jacomb <t.jacomb@kainos.com>

* Update core/src/test/java/hudson/slaves/NodeListTest.java
Co-Authored-By: NAdrien Lecharpentier <adrien.lecharpentier@gmail.com>

[JENKINS-34226] No "pressed" style for OK button on Create Item

* [JENKINS-41891] Resorce domain support

* Rename a few things

* Encapsulate token

* Update documentation based on review feedback

* Rename field and change symbol for friendlier JCasC format

* Be more explicit about expiration and URL sharing

* Allow favicon.ico, robots.txt; better logging

* Remove TODO from comment

* Consider resource root URL only set if the Jenkins root URL is set

* Improve form validation

* Clean up form validation warnings a bit

* Fix null handling (even though it'll never be called that way)

* Simpler logging statement after code review

* It's nicer to read this way

* Use the proper API for this with less string magic

* Update TODO comments

* Simplify log statement

* Use base64 instead of hexadecimal for shorter URLs

* Open link to Wikipedia in new tab/window

* Serve directory indexes

* Fix target of redirect in admin monitor

* Update TODO comments in test to current implementation

* Include link to parent directory unless in top level directory

* Update validation message when we cannot determine instance identity

* Improve tests

* Fix permission exception, further improve tests

* Annotation was redundant

* Add test for resource domain monitor activation

* Do not go through hex encoding/decoding

* Address review comments
Co-Authored-By: NJesse Glick <jglick@cloudbees.com>

* Address further review feedback

* Better logging, handle exception when the user is gone

* Only get the bytes once

* Inline help improvements
Co-Authored-By: NJeff Thompson <jeffret.g@gmail.com>

* Remove browser-based metadata download

* Fix Javadoc, add TODO

* Further cleanup

* Remove leftover reference to DownloadService from UI

* License header and note of origin for DailyCheck

* Add Javadoc with note about the update frequency

* removed deprecated TarOutputStream

* restored TarOutputStream and added @Restricted(NoExternalUse.class) to the class as suggested

* Added @Restricted(NoExternalUse.class) to TarInputStream

* added the @RestrictedSince(2.200) as suggested