presto-main/src/main/java/io/prestosql/split/PageSourceManager.java/PageSourceManager/addConnectorPageSourceProvider
class PageSourceManager:    public void addConnectorPageSourceProvider(CatalogName catalogName, ConnectorPageSourceProvider pageSourceProvider)
    {
        requireNonNull(catalogName, "catalogName is null");
        requireNonNull(pageSourceProvider, "pageSourceProvider is null");
        checkState(pageSourceProviders.put(catalogName, pageSourceProvider) == null, "PageSourceProvider for connector '%s' is already registered", catalogName);
    }