presto-cassandra/src/main/java/io/prestosql/plugin/cassandra/NativeCassandraSession.java/NativeCassandraSession/addWhereClause
class NativeCassandraSession:    private static void addWhereClause(Where where, List<CassandraColumnHandle> partitionKeyColumns, List<Object> filterPrefix)
    {
        for (int i = 0; i < filterPrefix.size(); i++) {
            CassandraColumnHandle column = partitionKeyColumns.get(i);
            Object value = column.getCassandraType().getJavaValue(filterPrefix.get(i));
            Clause clause = QueryBuilder.eq(CassandraCqlUtils.validColumnName(column.getName()), value);
            where.and(clause);
        }
    }