see more from https://github.com/openzipkin/brave/issues/867, also see https://github.com/apache/incubator-dubbo/issues/3576
/**
     * get local host.
     *
     * @return local host
     */
    public String getLocalHost() {
        String host = localAddress == null ? null :
                localAddress.getAddress() == null ? localAddress.getHostName()
                        : NetUtils.filterLocalHost(localAddress.getAddress().getHostAddress());
        if (host == null || host.length() == 0) {
            return NetUtils.getLocalHost();
        }
        return host;
    }
    /**
     * get local port.
     *
     * @return port
     */
    public int getLocalPort() {
        return localAddress == null ? 0 : localAddress.getPort();
    }
    /**
     * get remote host.
     *
     * @return remote host
     */
    public String getRemoteHost() {
        return remoteAddress == null ? null :
                remoteAddress.getAddress() == null ? remoteAddress.getHostName()