public static NewDocumentReferenceDataType forDocumentName(String documentName) {
        return new NewDocumentReferenceDataType(new DocumentType(documentName));
    }
Model for ReferenceDataType which is more suitable when
we want to end up with NewDocumentType as target type.

@author arnej
config-model/src/main/java/com/yahoo/documentmodel/NewDocumentReferenceDataType.java