Jenkins - Get the user who triggered the current or the parent job

get-started-by-user.groovy

def triggeredBy = "---"

def iterateCause(b) {
  upstreamcause = b.getCause(hudson.model.Cause.UpstreamCause.class)
  if (upstreamcause != null) {
    job = Jenkins.getInstance().getItemByFullName(upstreamcause.getUpstreamProject(), hudson.model.Job.class)
    if (job != null) {
      upstream = job.getBuildByNumber(upstreamcause.getUpstreamBuild())
      if (upstream != null) {
        iterateBuild(upstream)
      }
    }
  }

  usercause = b.getCause(hudson.model.Cause.UserIdCause.class)
  if (usercause != null) {
    triggeredBy = usercause.getUserName()
  }
  return;
}

iterateCause(build)

I wasn't authorized to use the rawBuild method, so I did it like this:

pipeline {
    agent any
    stages {
        stage('Print user') {
            steps {
                script {
                  if(currentBuild.upstreamBuilds){
                    print("Parent")
                    print(currentBuild.upstreamBuilds[0].getBuildCauses()[0].userId)
                  } else {
                    print("No parent")
                    print(currentBuild.getBuildCauses()[0].userId)
                  }
                }
            }
        }
    }
}