presto-kudu/src/main/java/io/prestosql/plugin/kudu/KuduClientSession.java/KuduClientSession/listTables
class KuduClientSession:    public List<SchemaTableName> listTables(Optional<String> optSchemaName)
    {
        if (optSchemaName.isPresent()) {
            return listTablesSingleSchema(optSchemaName.get());
        }

        List<SchemaTableName> all = new ArrayList<>();
        for (String schemaName : listSchemaNames()) {
            List<SchemaTableName> single = listTablesSingleSchema(schemaName);
            all.addAll(single);
        }
        return all;
    }