I can query a repo for its refs:

val toDelete = repo.listRefs().asList().filter { it.ref == "refs/heads/$version" || it.ref == "refs/heads/$otherVersion" }

but when I try to delete a ref:

toDelete.forEach {
    it.delete()
}

I get a NullPointerException because root is null within the GHRef for some reason.

What is the proper way of deleting a ref?

A workaround I found is to do this:

toDelete.forEach {
    repo.getRef(it.ref.replace("refs/", "")).delete()
}

This highlights another discrepancy: when I call getRef I have to remove the refs/ part to properly fetch the ref.