@Override
    public List<String> listDatabases() throws CatalogException {
        if (asNamespaceCatalog == null) {
            return Collections.singletonList(getDefaultDatabase());
        }

        return asNamespaceCatalog.listNamespaces(baseNamespace).stream()
                .map(n -> n.level(n.levels().length - 1))
                .collect(Collectors.toList());
    }
Append a new level to the base namespace
inlong-sort/sort-flink/sort-flink-v1.15/sort-connectors/iceberg/src/main/java/org/apache/inlong/sort/iceberg/FlinkCatalog.java