Check Git changes in `admin` dir

Jenkinsfile

        stage('Init') {

             steps {

                 script {

                     GIT_CHANGED_ADMIN = sh(returnStdout: true, script: "git diff-tree --name-only ${env.GIT_COMMIT} | grep admin | wc -l").trim().toBoolean()
                     echo "GIT_CHANGED_ADMIN = ${GIT_CHANGED_ADMIN}"

                 }

             }

         }