@Override
    long next() {
      index = nextIndex;
      if (index < 0) {
        throw new NoSuchElementException("no more elements available");
      }
      nextIndex = received.previousSetBit(index - 1);
      if (nextIndex + receivedBaseVersion <= previousVersion) {
        nextIndex = -1;
      }
      return index + receivedBaseVersion;
    }
it's a shame that BitSet has no iterator
geode-core/src/main/java/org/apache/geode/internal/cache/versions/RVVExceptionB.java