docs: public static IntIterator getCommonDimensions(Collection<SplitHistory> splitHistories) {
      Iterator<SplitHistory> it = splitHistories.iterator();
      long[] checkSet = BitsUtil.copy(it.next().dimBits);
      while(it.hasNext()) {
        SplitHistory sh = it.next();
        BitsUtil.andI(checkSet, sh.dimBits);
      }
      return new BitsetIterator(checkSet);
    }