"Build Periodically" with a Multi-branch Pipeline in Jenkins

I'm running Jenkins 2 with the Pipeline plugin. I have setup a Multi-branch Pipeline project where each branch (master, develop, etc.) has a Jenkinsfile in the root. Setting this up was simple. However, I'm at a loss for how to have each branch run periodically (not the branch indexing), even when the code does not change. What do I need to put in my Jenkinsfile to enable periodic builds?

If you use a declarative style Pipeline and only want to trigger the build on a specific branch you can do something like this:

String cron_string = BRANCH_NAME == "master" ? "@hourly" : ""

pipeline {
  agent none
  triggers { cron(cron_string) }
  stages {
    // do something
  }
}

Found on Jenkins Jira

If you are using a declarative style Jenkinsfile then you use the triggers directive.

pipeline {
    agent any
    triggers {
        cron('H 4/* 0 0 1-5')
    }
    stages {
        stage('Example') {
            steps {
                echo 'Hello World'
            }
        }
    }
}