How to use the node-opcua-service-endpoints.ApplicationType.DiscoveryServer function in node-opcua-service-endpoints

function _isValidServerType(serverType: ApplicationType): boolean {

    switch (serverType) {
        case ApplicationType.Client:
            return false;
        case ApplicationType.Server:
        case ApplicationType.ClientAndServer:
        case ApplicationType.DiscoveryServer:
            return true;
    }
    return false;
}

constructor(options: OPCUADiscoveryServerOptions) {

        const default_certificate_file = constructFilename("certificates/server_selfsigned_cert_2048.pem");
        options.certificateFile = options.certificateFile || default_certificate_file;
        assert(fs.existsSync(options.certificateFile));

        const default_private_key_file = constructFilename("certificates/PKI/own/private/private_key.pem");
        options.privateKeyFile = options.privateKeyFile || default_private_key_file;
        assert(fs.existsSync(options.certificateFile));

        const defaultApplicationUri = makeApplicationUrn("%FQDN%", "NodeOPCUA-DiscoveryServer");

        options.serverInfo = options.serverInfo || {};
        const serverInfo = options.serverInfo;
        serverInfo.applicationType = ApplicationType.DiscoveryServer;
        serverInfo.applicationUri = serverInfo.applicationUri || defaultApplicationUri;
        serverInfo.productUri = serverInfo.productUri || "NodeOPCUA-DiscoveryServer";
        serverInfo.applicationName = serverInfo.applicationName || { text: "NodeOPCUA-DiscoveryServer", locale: null };
        serverInfo.gatewayServerUri = serverInfo.gatewayServerUri || "";
        serverInfo.discoveryProfileUri = serverInfo.discoveryProfileUri || "";
        serverInfo.discoveryUrls = serverInfo.discoveryUrls || [];

        super(options);

        this.bonjourHolder = new BonjourHolder();

        const port = options.port || 4840;

        this.capabilitiesForMDNS = ["LDS"];
        this.registeredServers = {};