@Override
  public boolean hasNext() {
    return nextClearBit != -1;
  }
Find the next clear bit from a given index in the bitset, that is less than or
equal to our maximum version for this iterator.

@return the next clear bit, or -1 if there is no next clear bit within the range.
geode-core/src/main/java/org/apache/geode/internal/cache/versions/BitSetExceptionIterator.java