presto-main/src/main/java/io/prestosql/metadata/CatalogManager.java/CatalogManager/registerCatalog
class CatalogManager:    public synchronized void registerCatalog(Catalog catalog)
    {
        requireNonNull(catalog, "catalog is null");

        checkState(catalogs.put(catalog.getCatalogName(), catalog) == null, "Catalog '%s' is already registered", catalog.getCatalogName());
    }