StationListRest.java

public static void GetStationList(final String contract, final ICallBackStation oCallBack, Context context){
    RestService restService = GetRetrofitService();
    HashMap<String, String> queryMap = new HashMap<>();
    queryMap.put("apiKey", "XXXXXXXXXXXXXXX");
    queryMap.put("contract", contract);
   
    Call<List<StationReply>> call = restService.getStationList(queryMap);

    call.enqueue(new Callback<List<StationReply>>() {
        @Override
        public void onResponse(Call<List<StationReply>> call, Response<List<StationReply>> response) {
        }

        @Override
        public void onFailure(Call<List<StationReply>> call, Throwable t) {
        }
    });
}