code: private void updateObservedReplicaTimestamps(VectorClock receivedVectorClock) {
          for (; ; ) {
              final VectorClock currentClock = this.observedClock;
              if (currentClock != null && currentClock.isAfter(receivedVectorClock)) {
                  break;
              }
              if (OBSERVED_TIMESTAMPS_UPDATER.compareAndSet(this, currentClock, receivedVectorClock)) {
                  break;
              }
          }
      }
docs: Updates the locally observed CRDT vector clock atomically. This method
  is thread safe and can be called concurrently. The method will only
  update the clock if the {@code receivedLogicalTimestamps} is higher than
  the currently observed vector clock.
  
  @param receivedVectorClock vector clock received from a replica state read