}
public static String checkpoint(Document document) throws RepositoryException {
String uuid = Value.getSingleValueString(document,
SpiConstants.PROPNAME_DOCID);
DateValue dateValue = (DateValue) Value.getSingleValue(document,
SpiConstants.PROPNAME_LASTMODIFIED);
String dateString = dateValue.toIso8601();
String result = null;
try {
JSONObject jo = new JSONObject();
jo.put("uuid", uuid);
jo.put("lastModified", dateString);