code: @Override
      @Transactional
      public Snapshot updateHistory(Snapshot snapshot, String history) {
          snapshot = this.snapshotRepo.getOne(snapshot.getId());
          SnapshotHistory newHistory = new SnapshotHistory();
          newHistory.setHistory(history);
          newHistory.setSnapshot(snapshot);
          snapshot.getSnapshotHistory().add(newHistory);
          return this.snapshotRepo.save(snapshot);
      }
docs: /* (non-Javadoc)
  @see org.duracloud.snapshot.service.SnapshotManager#updateHistory()