@Override
  public Identifier[] listTables(String[] namespace) {
    List<String> database;
    if (namespace == null || namespace.length == 0) {
      database = catalog.listDatabases();
    } else {
      database = new ArrayList<>();
      database.add(namespace[0]);
    }

    List<TableIdentifier> tableIdentifiers =
        database.stream()
            .map(d -> catalog.listTables(d))
            .flatMap(Collection::stream)
            .collect(Collectors.toList());

    return tableIdentifiers.stream()
        .map(i -> Identifier.of(new String[] {i.getDatabase()}, i.getTableName()))
        .toArray(Identifier[]::new);
  }
Base class of mixed-format spark catalog.
amoro-format-mixed/amoro-mixed-spark/amoro-mixed-spark-3-common/src/main/java/org/apache/amoro/spark/mixed/MixedSparkCatalogBase.java