docs: public static ListenableFuture<SnapshotCompletionInterest.SnapshotCompletionEvent>
      watchSnapshot(final String nonce)
      {
          final SettableFuture<SnapshotCompletionInterest.SnapshotCompletionEvent> result =
              SettableFuture.create();
  
          SnapshotCompletionInterest interest = new SnapshotCompletionInterest() {
              @Override
              public CountDownLatch snapshotCompleted(SnapshotCompletionEvent event)
              {
                  if (event.nonce.equals(nonce) && event.didSucceed) {
                      VoltDB.instance().getSnapshotCompletionMonitor().removeInterest(this);
                      result.set(event);
                  }
                  return null;
              }
          };
          VoltDB.instance().getSnapshotCompletionMonitor().addInterest(interest);
  
          return result;
      }