presto-cassandra/src/main/java/io/prestosql/plugin/cassandra/CassandraRecordCursor.java/CassandraRecordCursor/getSlice
class CassandraRecordCursor:    @Override
    public Slice getSlice(int i)
    {
        NullableValue value = CassandraType.getColumnValue(currentRow, i, cassandraTypes.get(i));
        if (value.getValue() instanceof Slice) {
            return (Slice) value.getValue();
        }
        return utf8Slice(value.getValue().toString());
    }