private void delete(List<PurgeableSnapshotDto> snapshots, DbSession session) {
   for (PurgeableSnapshotDto snapshot : snapshots) {
     LOG.debug(
         "<- Delete snapshot: {} [{}]",
         DateUtils.formatDateTime(snapshot.getDate()),
         snapshot.getSnapshotId());
     purgeDao.deleteSnapshots(
         PurgeSnapshotQuery.create().setRootSnapshotId(snapshot.getSnapshotId()), session);
     purgeDao.deleteSnapshots(
         PurgeSnapshotQuery.create().setId(snapshot.getSnapshotId()), session);
   }
 }