pipeline {
  agent any
  stages {
    stage('build') {
      steps {
        buildComponents items: ("a".."f").collect { "Stage ${it}" }
      }
    }
    stage('build2') {
          steps {
            buildComponents items: ("g".."p").collect { "Stage ${it}" }
          }
        }
  }
}

def buildComponents(args) {
  parallel args.items.collectEntries { name -> [ "${name}": {
    stage("${name}") {
      echo name
    }
  }]}
}