presto-main/src/main/java/io/prestosql/metadata/StaticCatalogStore.java/StaticCatalogStore/loadCatalogs
class StaticCatalogStore:    public void loadCatalogs()
            throws Exception
    {
        if (!catalogsLoading.compareAndSet(false, true)) {
            return;
        }

        for (File file : listFiles(catalogConfigurationDir)) {
            if (file.isFile() && file.getName().endsWith(".properties")) {
                loadCatalog(file);
            }
        }
    }