private ListNamespacesResponse listNamespaces(Map<String, String> vars) {
    if (asNamespaceCatalog != null) {
      Namespace namespace;
      if (vars.containsKey("parent")) {
        namespace = Namespace.of(RESTUtil.NAMESPACE_SPLITTER.splitToStream(vars.get("parent")).toArray(String[]::new));
      } else {
        namespace = Namespace.empty();
      }
      return castResponse(ListNamespacesResponse.class, CatalogHandlers.listNamespaces(asNamespaceCatalog, namespace));
    }
    throw new NamespaceNotSupported(catalog.toString());
  }
@param apis an optional list of known api call names
@return the list of metric names for the HMSCatalog class
standalone-metastore/metastore-rest-catalog/src/main/java/org/apache/iceberg/rest/HMSCatalogAdapter.java