Git changelog plugin use in pipeline: missing functions?

I’m trying to start using the gitChangelog plugin in a pipeline, but I have questions:

  • is there a way to specify the template as a file in workspace? Or do I have to use a utility step and read the file into a string?

  • How do you specify “from start of repo”? Omit the “from” parameter? Or is there a token value to provide? I see this in the freestyle step, but not in the snippets generator

I can’t find answers in the docs or searching around, hoping someone here can help. Thanks in advance.