@Override
 public DBCursor findEvents(
     DBCollection collection, String aggregateIdentifier, long firstSequenceNumber) {
   return collection
       .find(CommitEntry.forAggregate(aggregateIdentifier, firstSequenceNumber))
       .sort(new BasicDBObject(CommitEntry.SEQUENCE_NUMBER_PROPERTY, ORDER_ASC));
 }
 @Override
 public String getAggregateIdentifier() {
   return commitEntry.getAggregateIdentifier();
 }