pipeline {
    agent any 
    stages {
        stage('Checkout') {
            steps {
                checkout([$class: 'GitSCM',
                          branches: [[name: '*/master']],
                          doGenerateSubmoduleConfigurations: false,
                          extensions: [],
                          submoduleCfg: [],
                          userRemoteConfigs: [[url: 'https://github.com/username/repository.git']]])
            }
        }
        stage('Stage 1') {
            steps {
                echo 'Hello world!' 
            }
        }
    }
}