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JENKINS-61208 System read - admin monitor pattern

JEP-224 System read - Global tool configuration

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Fix comment about when this is set

Bump parent pom to 1.55

[JENKINS-61905] Forward Groovy view permission errors to login

[JENKINS-61840] Restyle buttons

More Javadoc to help implementers, simplify code a bit

[JENKINS-61932] Fix redirect URL

Make the timestamp on the footer more compact

- e66df306 broke this test when removing the button nested within the anchor

[JENKINS-60866] Un-inline JavaScript/Style in Job views

* Draft the new maintainer guide

* Maintainer guide - Apply suggestions from code review
Co-Authored-By: NRaihaan Shouhell <raihaanhimself@gmail.com>
Co-Authored-By: NTim Jacomb <t.jacomb@kainos.com>
Co-Authored-By: NDaniel Beck <1831569+daniel-beck@users.noreply.github.com>

* Apply suggestions from code review
Co-Authored-By: NJeff Thompson <37345299+jeffret-b@users.noreply.github.com>
Co-Authored-By: NFrancisco Fernández <31063239+fcojfernandez@users.noreply.github.com>

* Maintainer guide - Replace the first role by "contributor"

* Maintainer guide - Add more details

* Maintainer guide - address some feedback

* Apply suggestions from code review by @daniel-beck
Co-Authored-By: NDaniel Beck <1831569+daniel-beck@users.noreply.github.com>

* Update .github/PULL_REQUEST_TEMPLATE.md
Co-Authored-By: NDaniel Beck <1831569+daniel-beck@users.noreply.github.com>

* Maintainer guide - more updates

* Maintainer Guide: Add info about the Security Releases and merges + add an explicit Jenkins LTS section

Addresses comments from @daniel-beck and @olivergondza

* Maintainer guide: reference the advisories

* Apply suggestions from code review
Co-Authored-By: NMark Waite <mark.earl.waite@gmail.com>
Co-Authored-By: NRaihaan Shouhell <raihaanhimself@gmail.com>
Co-Authored-By: NDaniel Beck <1831569+daniel-beck@users.noreply.github.com>

* Apply suggestions from code review
Co-Authored-By: NMark Waite <mark.earl.waite@gmail.com>

* Fix typos

* Expand code review goals: documentation and code styles

* Maintainer guide: Document the squash-merge policy

* Apply suggestions from code review
Co-Authored-By: NMark Waite <mark.earl.waite@gmail.com>
Co-authored-by: NRaihaan Shouhell <raihaanhimself@gmail.com>
Co-authored-by: NTim Jacomb <t.jacomb@kainos.com>
Co-authored-by: NDaniel Beck <1831569+daniel-beck@users.noreply.github.com>
Co-authored-by: NJeff Thompson <37345299+jeffret-b@users.noreply.github.com>
Co-authored-by: NFrancisco Fernández <31063239+fcojfernandez@users.noreply.github.com>
Co-authored-by: NMark Waite <mark.earl.waite@gmail.com>

[JENKINS-61711] Fix validateExecutable to allow Git plugin global config correctly report git executable in PATH (#4653)

* Fix git not in path for Git plugin global config
Git Client Plugin global configuration allows addition of git implementations using GitTool
The field Path was not able to identify git executable. The fix involves changing prefix with
File.seperator instead of File.pathSeperator. This allows Jenkins to find the git exec at the
already existing path.

* Tests added to validate JENKINS-61711 fix

* Improve hamcrest comparison in FormValidationTest
Co-Authored-By: NMark Waite <mark.earl.waite@gmail.com>

* Import matchers for `not`
Co-authored-by: NMark Waite <mark.earl.waite@gmail.com>

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

Co-Authored-By: NTim Jacomb <t.jacomb@kainos.com>

- Now that the anchor tags with a .yui-button class are styled like buttons, it is unnecessary to add a button within.

- Disables default YahooUI button styles
- Use YUI classes for backwards compatibility:
    - <span class="yui-button"><button>Button element</button>
- Styles are applied by default for the following input types:
    - <input type="[button | reset | submit]" />
- Add a large button variant
    - The variant is set adding the .large-button class
    - f:apply and f:submit jelly templates now have a isLarge property that allows toggling large buttons on
    - Job configuration has large buttons