Pipeline: jenkins initial checkout with TFS LABEL

I’m using jenkins/jenkins:lts container and use TFS-plugin fixed version.

As described in GitHub - jenkinsci/tfs-plugin: Jenkins tfs plugin if I define a job with a parameter named VERSION_SPEC, I can build my project using a LABEL version of source code, and this works as expected.

If I define a pipeline with one parameter named VERSION_SPEC and a jenkinsfile, the initial checkout executed by jenkins in order to get jenkinsfile doesn’t get the labeled version and get the latest version.

If I print the environment in the pipeline, I can see that the variable is defined.

I can’t figure out what is wrong in what I did, so can someone help me please?