YAML->RDF won't produce a complete file in some cases

moved from https://github.com/common-workflow-language/common-workflow-language/issues/171
@ntijanic commented on 30 Nov 2015

> Some ordering is lost in conversion, but this could be fixed by setting `@container: @list` in the context for these fields: `engineConfig` and `source`.
>
> Also, `default` field can in theory include a map or a list. Not sure how to deal with this. Some options:
> - Allow only primitive values for `default` (no maps, lists or files).
> - Require maps and lists to be represented in another way e.g. `class: SerializedValue, value: `.
> - Drop the idea that execution semantics survive loading to RDF graph.
>
> I suggest we temporarily disallow maps and lists for `default`, and introduce support in future iteration.
>
>