I'm using Jenkins Job DSL.

I found 'TAG' does not fetch any tag soon after building seed job, although it does after I move to job configuration and pushing Save button.

Here is minimal code to reproduce the issue:

job('gitParam-doesnt-fetch-tags') {
  scm {
    git {
      remote {
        branch('**')
        url('git@gitlab.our-company.com:organization/repo.git')
        credentials('our-gitlab-user-pass')
      }
    }
  }
  parameters {
    gitParam('GIT_TAG') {
      type('TAG')
    }
  }
}

Workaround

Use GitParameterDefinition() instead of gitParam().

job('gitParam-doesnt-fetch-tags') {
  scm {
    git {
      remote {
        branch('**')
        url('git@gitlab.our-company.com:organization/repo.git')
        credentials('our-gitlab-user-pass')
      }
    }
  }
  parameters {
    buildParameterNodes['GIT_TAG'] = NodeBuilder.newInstance().'net.uaznia.lukanus.hudson.plugins.gitparameter.GitParameterDefinition' {
      name('GIT_TAG')
      type('PT_TAG')
      sortMode('DESCENDING_SMART') // this seems required
    }
  }
}

Detailed explanation of the issue

After building seed job, I get this job to reproduce the issue.

When I move to "Parameterized build", no git tags are displayed.

After moving to configuration, changing nothing, and pushing Save button,

then parameterized build screen shows tags as I expected.