public static ParsedType documentRef(ParsedType docType) {
        assert(docType != null);
        return new ParsedType("reference<" + docType.name + ">", Variant.DOC_REFERENCE, docType);
    }
This class holds the extracted information after parsing a type
declaration (typically for a field).  Since types can be complex,
struct names (known or unknown), or even document names, this class
is somewhat complicated.
@author arnej27959
config-model/src/main/java/com/yahoo/schema/parser/ParsedType.java