presto-cassandra/src/main/java/io/prestosql/plugin/cassandra/CassandraTable.java/CassandraTable/getClusteringKeyColumns
class CassandraTable:    public List<CassandraColumnHandle> getClusteringKeyColumns()
    {
        return columns.stream()
                .filter(CassandraColumnHandle::isClusteringKey)
                .collect(toImmutableList());
    }