presto-main/src/main/java/io/prestosql/connector/system/SystemTablesMetadata.java/SystemTablesMetadata/listTables
class SystemTablesMetadata:    @Override
    public List<SchemaTableName> listTables(ConnectorSession session, Optional<String> schemaName)
    {
        return tables.listSystemTables(session).stream()
                .map(SystemTable::getTableMetadata)
                .map(ConnectorTableMetadata::getTable)
                .filter(table -> !schemaName.isPresent() || table.getSchemaName().equals(schemaName.get()))
                .collect(toImmutableList());
    }