background to this:
1. EpicEditor JS library, set up to use Asciidoctor.js as an EpicEditor plugin. for more info, see https://github.com/OscarGodson/EpicEditor/issues/380
2. Markitup (http://markitup.jaysalvat.com/home/), using https://github.com/lordofthejars/asciidoctor-markitup
In terms of programming model, could either introduce a new value type, eg Asciidoc, or extend @Property and @Parameter (or should it be @PropertyLayout and @ParameterLayout). I think I prefer the former, as is more encapsulated.
Or, perhaps reuse Clob, but find a way to provide a hint that the content is asciidoc.