Verify the version past the Guava & Guice bumps (#140)

* No-op change to check CI result

I suspect some unrelated problem to another change I'm trying to submit.

* Verify the version past the Guava & Guice bumps

jenkinsci/jenkins#5707
jenkinsci/jenkins#5858

* Add missing comma

* Remove JDK8 builds

Co-authored-by: Ivan Fernandez Calvo <kuisathaverat@users.noreply.github.com>

Co-authored-by: Ivan Fernandez Calvo <kuisathaverat@users.noreply.github.com>

Jenkinsfile

@@ -1,6 +1,12 @@
 #!/usr/bin/env groovy
 
-buildPlugin(useContainerAgent: true, configurations: [
-  [ platform: "windows", jdk: "11" ],
-  [ platform: "linux", jdk: "11" ]
-])
+buildPlugin(useContainerAgent: true,
+        configurations: [
+                [platform: 'linux', jdk: '11'],
+                [platform: 'windows', jdk: '11'],
+
+                // testing the Guava & Guice bumps
+                // https://github.com/jenkinsci/jenkins/pull/5707
+                // https://github.com/jenkinsci/jenkins/pull/5858
+                [ platform: "linux", jdk: "11", jenkins: '2.321', javaLevel: "8" ]
+        ])

README.md

@@ -40,5 +40,3 @@ Report new issue on https://issues.jenkins-ci.org on component **saml-plugin**.
 [How to report an issue](https://wiki.jenkins.io/display/JENKINS/How+to+report+an+issue)
 
 **The Jenkins JIRA is not a support site. If you need assistance or have general questions, visit us [in chat](http://jenkins-ci.org/content/chat), or email one of the [mailing lists](http://jenkins-ci.org/content/mailing-lists).**
-
-