presto-cassandra/src/main/java/io/prestosql/plugin/cassandra/CassandraSplitManager.java/CassandraSplitManager/createSplitForClusteringPredicates
class CassandraSplitManager:    private CassandraSplit createSplitForClusteringPredicates(
            String partitionId,
            List<HostAddress> hosts,
            String clusteringPredicates)
    {
        if (clusteringPredicates.isEmpty()) {
            return new CassandraSplit(partitionId, null, hosts);
        }

        return new CassandraSplit(partitionId, clusteringPredicates, hosts);
    }