// пример запроса
http://fe-ct.svc.iptv.rt.ru/smarttube/master/spine/services/json/ott/get_network_config?uid=123321

// response класс для него
public class NetworkConfigRs extends Rs {

    public static class Url {
        @SerializedName("url")
        public String url;
    }

    public static class Data {
        @SerializedName("frontend")
        public Url frontend;
        @SerializedName("proxy")
        public Url proxy;
        @SerializedName("deviceType")
        public String deviceType;
        @SerializedName("homeMrf")
        public String homeMrf;
        @SerializedName("curMrf")
        public String curMrf;
        @SerializedName("curLocation")
        public String curLocation;
        @SerializedName("curSubLocation")
        public String curSubLocation;

        @Override
        public String toString() {
            return "Data{" +
                    "frontend=" + frontend +
                    ", proxy=" + proxy +
                    ", deviceType='" + deviceType + '\'' +
                    ", homeMrf='" + homeMrf + '\'' +
                    ", curMrf='" + curMrf + '\'' +
                    ", curLocation='" + curLocation + '\'' +
                    ", curSubLocation='" + curSubLocation + '\'' +
                    '}';
        }
    }

    public static class Rows {
        public Data[] data;
    }

    @SerializedName("rows")
    public Rows rows;

}

 // использование этого класса
    NetworkConfigRs rs = methodsServerSDP.getNetworkConfig("123321", null);
    String url = rs.rows.data[0].frontend.url;