Retrofit for Eventful example

EventfulApiModel.java

public class EventsRequestModel {

    public class EventsModelResponse {
        @SerializedName(EventfulApiKeys.JSON_KEY_EVENTS)
        EventsMainSection eventsMainSection;

        public List<EventGson> getListEvents (){
            return eventsMainSection.eventsPackage.listEvents;
        }
    }

    private class EventsMainSection {
        @SerializedName(EventfulApiKeys.JSON_KEY_PACKAGE_EVENTS)
        EventsPackage eventsPackage;
    }

    private class EventsPackage {
        @SerializedName(EventfulApiKeys.JSON_KEY_EVENTS)
        List<EventGson> listEvents;
    }

    public class EventGson {
        @SerializedName(EventfulApiKeys.JSON_KEY_TITLE_EVENT)
        String title;

        @SerializedName(EventfulApiKeys.JSON_KEY_DATE_EVENT)
        String date;

        @SerializedName(EventfulApiKeys.JSON_KEY_DESCRIPTION_EVENT)
        String description;

        public String getTitle() {
            return title;
        }

        public String getDate() {
            return date;
        }

        public String getDescription() {
            return description;
        }
    }
}

RetrofitClient.java

public class EventfulApiClient {

    private EventfulApiContract apiContract;

    public EventfulApiClient() {

        RestAdapter restAdapter = new RestAdapter.Builder()
                .setLogLevel(RestAdapter.LogLevel.BASIC)
                .setEndpoint(EventfulApiKeys.BASE_URL)
                .build();

        apiContract = restAdapter.create(EventfulApiContract.class);
    }

    public EventfulApiContract getApiContract() {
        return apiContract;
    }
}

RetrofitRequest.java

EventfulApiClient retrofitClient = new EventfulApiClient();

        retrofitClient.getApiContract().findEvents(EventfulApiKeys.APP_KEY , EventfulApiKeys.VALUE_THIS_WEEK , location,
            new Callback<EventsRequestModel.EventsModelResponse>() {
                @Override
                public void success(EventsRequestModel.EventsModelResponse eventsModelResponse,
                                    retrofit.client.Response response) {

                    EventsRequestModel.EventGson randomEvent = eventsModelResponse.getListEvents().get(0);
                    changeEventUI(randomEvent.getTitle(), randomEvent.getDate(), randomEvent.getDescription());
                }

                @Override
                public void failure(RetrofitError error) {

                }
            });

RetrofitService.java

@GET(EventfulApiKeys.URL_EVENTS_SEARCH)
    public void findEvents(@Query(EventfulApiKeys.PARAM_APP_KEY) String appKey ,
                           @Query(EventfulApiKeys.PARAM_DATE) String date,
                           @Query(EventfulApiKeys.PARAM_LOCATION) String location,
                               retrofit.Callback<EventsRequestModel.EventsModelResponse> eventsCallback);