In order to enable the support of JDK11 for Jenkins and its plugins, the Jenkinsfile of plugins should be completed allowing to build and test the plugin using JDK11 as well as JDK8.

The configuration we propose to apply is the following:

buildPlugin(configurations: [  [platform: 'linux', jdk: '8'],  [platform: 'linux', jdk: '11'],  [platform: 'windows', jdk: '11'], ])

The goal is to allow building and testing over JDK11 for both Windows & Linux.

Building and testing over JDK8 will still be kept for Linux.

We also propose to keep only one Windows flavor in order to save infrastructure costs, hence having only JDK11 for Windows.