When running with the following Jenkinsfile:

node {
    checkout scm
    echo "My branch is: ${env.BRANCH_NAME}"
    echo "My target branch is: ${env.CHANGE_TARGET}"
}

The following is printed out:

[Pipeline] echo
My branch is: PR-4
[Pipeline] echo
My target branch is: null

I thought CHANGE_TARGET would contain the target branch but apparently I am mistaken? The setup I was thinking of is the following:

Pull request (from a fork):

• merge with target branch
• run test suite

Pull request get merged into a release branch

• run test suite
• build and deploy/publish an artifact

But it seems to be impossible to declare this in a single folder, I would also be happy to do this in two folders, but that seems impossible as well?

If there was a way to differentiate between a PR and a regular build AND get the target branch for a PR, I could keep Jenkins config to the bare minimum; the link to a repo and let multibranch / pr discovery do all the rest.

Am I maybe missing something obvious here or am I trying to do the impossible? I combed through the documentation for the plugin and the available docs and snippet generator for the pipeline scripts but came up empty.