https://github.com/jenkinsci/build-user-vars-plugin/pull/16
you can build by your self: mvn -DskipTests=true -s $PWD/../jenkins-core/settings-azure.xml package
$PWD/../jenkins-core/settings-azure.xml this file is from jenkins-core git
see https://github.com/mamh-java/build-user-vars-plugin/commits/master