presto-iceberg/src/main/java/io/prestosql/plugin/iceberg/IcebergMetadata.java/IcebergMetadata/listTables
class IcebergMetadata:    @Override
    public List<SchemaTableName> listTables(ConnectorSession session, Optional<String> schemaName)
    {
        return schemaName.map(Collections::singletonList)
                .orElseGet(metastore::getAllDatabases)
                .stream()
                .flatMap(schema -> metastore.getTablesWithParameter(schema, TABLE_TYPE_PROP, ICEBERG_TABLE_TYPE_VALUE).stream()
                        .map(table -> new SchemaTableName(schema, table))
                        .collect(toList())
                        .stream())
                .collect(toList());
    }