CSTs with OTB connected systems

Question

Can we create CSTs with OTB connected systems, instead of extending the SimpleConnectedSystemTemplate? If so, how would we set up the appian-plugin.xml? 
 I ask because I see the beta has a new standard connected system type which ideally makes use of Google's json based authentication files (the HTTP / Google Service Account type), and I don't see a way to recreate that functionality in the javadocs for CSTs. As a fallback, we could just enter the fields in the json as separate encrypted text fields, but the question is of independent interest.

Jacob Rank · Accepted Answer

Right now it's not possible, but it's something we discussed just the other day related to the same Google Service Account situation you describe. We created the OAuth2 authorization code template since the 3-legged interaction there wasn't something that could easily be recreated from individual input fields. My hope is that most other authentication methods can be handled with existing capabilities but that in the future we could release patterns or base classes to give you a quicker and more consistent way to get basic auth, api key, etc.