Configuration of includedRegions in Jenkinsfile?
There is an open issue preventing proper function: https://issues.jenkins-ci.org/browse/JENKINS-36195
It has a workaround, which is to disable remote polling ([$class: 'DisableRemotePoll']):
checkout([$class: 'GitSCM', branches: [[name: "*/master"]], extensions: [ [$class: 'PathRestriction', excludedRegions: '', includedRegions: '<fill me in with regex \n delimited, leave excludedRegions as empty>'], [$class: 'DisableRemotePoll'] ], submoduleCfg: [], userRemoteConfigs: [[url: "<my git url>", credentialsId: "$GIT_KEY"]]])