Display document system properties in gadget

Gadgets can only display document properties extracted from schemas (referenced in the gadget with the attribute operationDocumentProperties)
So there's nothing to display, the document type, the lifecycle state, the path or uid, except writing a new displayMethod, whereas these properties are exposed in the JSON response/document.

Now these properties will be displayed using the keyword 'system' for the column definition.
For instance:

{type: 'system', field: 'state', label: '__MSG_label.state__', i18n: true}

in the same time, the attribute i18n will indicate that the value has to be translated, in a translation is available in dynamics messages