jenkins-job-builder/tests/yamlparser/job_fixtures/tag_in_parameter-join.yaml

# !join: tag in a variable.

- job-template:
    name: sample-job
    var: !join:
      - ' '
      - [some, variable]
    builders:
      - shell: |
          echo {var}          

- project:
    name: sample-project
    jobs:
      - sample-job