presto-main/src/main/java/io/prestosql/connector/ConnectorManager.java/ConnectorManager/addConnectorFactory
class ConnectorManager:    public synchronized void addConnectorFactory(ConnectorFactory connectorFactory, Supplier<ClassLoader> duplicatePluginClassLoaderFactory)
    {
        requireNonNull(connectorFactory, "connectorFactory is null");
        requireNonNull(duplicatePluginClassLoaderFactory, "duplicatePluginClassLoaderFactory is null");
        checkState(!stopped.get(), "ConnectorManager is stopped");
        InternalConnectorFactory existingConnectorFactory = connectorFactories.putIfAbsent(
                connectorFactory.getName(),
                new InternalConnectorFactory(connectorFactory, duplicatePluginClassLoaderFactory));
        checkArgument(existingConnectorFactory == null, "Connector '%s' is already registered", connectorFactory.getName());
    }