branch : master , version : 2.7.0-SNAPSHOT
ServiceConfig#doExportUrlsFor1Protocol , line 482

<img width="890" alt="image" src="https://user-images.githubusercontent.com/6971152/41273922-035827c2-6e4e-11e8-8a72-71562d138cf9.png">

The type of Constant.SCOPE_Xxx is String already , no need to call toString() again
protocol = protocol.toLowerCase();
        if (RANDOM_PORT_MAP.containsKey(protocol)) {
            return RANDOM_PORT_MAP.get(protocol);
        }
        return Integer.MIN_VALUE;
    }
    private static void putRandomPort(String protocol, Integer port) {
        protocol = protocol.toLowerCase();
        if (!RANDOM_PORT_MAP.containsKey(protocol)) {
            RANDOM_PORT_MAP.put(protocol, port);
        }
    }
    public URL toUrl() {
        return urls.isEmpty() ? null : urls.iterator().next();
    }
    public List<URL> toUrls() {
        return urls;
    }
    @Parameter(excluded = true)
    public boolean isExported() {
        return exported;
    }
    @Parameter(excluded = true)
    public boolean isUnexported() {
        return unexported;
    }
    public synchronized void export() {
        if (provider != null) {
            if (export == null) {
                export = provider.getExport();