pipeline {
    agent any
    stages {
        stage('Lock wrapper') {
            options {
              lock('resource')
            }     
            stages {
                stage('Sequential 1') {
                    steps {
                        echo "Sequential 1"
                    }
                }
                stage('Sequential 2') {
                    parallel {
                        stage('Parallel 2a') {
                            steps {
                                echo "Parallel 2a"
                            }
                        }
                    }
                }
            }
        }
    }
}