Copying over some of the questions and discussions from Gitter channel:

1) Would this be done by using a process builder and calling the mvn dependency plugin? It looked like this is what was being done in the Custom War Packager
2) Since this would require the groupId, should the plugins.txt file and plugin CLIOption input format be changed so that it could accept the groupId as a parameter? Or if the user wants to download plugins from the maven repository, they would enter this in a yaml file or some other method?

Feedback from Tim Jacomb and Kristin Whetstone:

Yaml files would be similer, don't want to change plugins.txt format too much 

The way that the custom war packager is doing it is right; some of the "dependencies" might not be plugins but most will be.

Some questions: 

1) Should a user be able to enter plugins they want to download from the update center and from maven during the same run of the CLI Tool? 

2) Should the yaml file entered to specify plugins from maven be different from the yaml file used by configuration as code? 

1) Yes. each plugin should be processed separately, I don't see why individual lines can't specify where the download happens.
2) Tim Jacomb would be in a better position to answer this. I think they should be together, but I'm not very involved with CasC.

2) Yes can be together.