I want to download an Artifact in a job present in a Child pipeline from another job present in another Child pipeline part of the same parent-child pipeline hierarchy. 

I tried with the files below that are inspired from the Gitlab documentation (see the paragraph "Example of needs:pipeline:job" in https://docs.gitlab.com/ee/ci/yaml/) but **with no success** (I have this error : *This job depends on other jobs with expired/erased artifacts*)

parent.yml

    parent1:
      stage: test
      trigger:
        include: child1.yml
        strategy: depend
    
    parent2:
      stage: test
      trigger:
        include: child2.yml
        strategy: depend
      variables:
        PARENT_PIPELINE_ID: $CI_PIPELINE_ID

Child1.yml

    create-artifact:
      stage: build
      script: echo "sample artifact" > artifact.txt
      artifacts:
        paths: [artifact.txt]

Child2.yml

    use-artifact:
      script: cat artifact.txt
      needs:
        - pipeline: $PARENT_PIPELINE_ID
          job: create-artifact


So according to the official Gitlab documentation : *A child pipeline can download artifacts from a job in its parent pipeline or another child pipeline in the same parent-child pipeline hierarchy.* so I am wondering how to make it work in my example files?