code: private static long getMaxTTL(Map<byte[], Long> ttlByFamily) {
      long maxTTL = 0;
      for (Long familyTTL : ttlByFamily.values()) {
        maxTTL = Math.max(familyTTL <= 0 ? Long.MAX_VALUE : familyTTL, maxTTL);
      }
      return maxTTL == 0 ? Long.MAX_VALUE : maxTTL;
    }
docs: Returns the max TTL for the given TTL values. Returns Long.MAX_VALUE if any of the column families has no TTL set.