v0.8: multiple types for parameter is not supported

[nidi3]

The example from the spec gives 2 ValidationResults:

Invalid element {
    type: string, 
    description: Text content. The text content must be the last field in the form.
}.
Invalid element {
    type: file,
    description: File to upload. The file must be the last field in the form.
}.

Aha! Link: https://mulesoft-roadmap.aha.io/features/APIRAML-106

[benken-parasoft]

This is blocking me from using raml-parser-2. I have to fall back to using raml-parser for this case.