在改造响应是200但我得到null

Question

我使用牛津词典API（https://developer.oxforddictionaries.com/）

并使用改进2来解析JSON

但是HTTP响应是200，但我得到空响应主体

public class WeatherApiRequest {


public static void getWeatherForecast(String language ,String word, Callback<WeatherForecast> callback) {

    Retrofit retrofit = RetrofitBuilder.getRetrofit();
    WeatherAPIs weatherAPIs = retrofit.create(WeatherAPIs.class);
    Call<WeatherForecast> weatherForecast = weatherAPIs.getWeatherForecast(language ,word );
    weatherForecast.enqueue(callback);
}

我的界面是：

public interface WeatherAPIs {

@Headers({
        "Accept: application/json",
        "app_id: {my-app_id}",
        "app_key: {my-app-key}"
})


@GET("entries/{source_lang}/{word_id}")
Call<WeatherForecast> getWeatherForecast(@Path("source_lang") String language, @Path("word_id") String word);

}

我制作这个模型：

public class WeatherForecast {

@SerializedName("provider")
@Expose
private String provider;

public String getProvider() {
    return provider;
}

public void setProvider(String provider) {
    this.provider = provider;
}

}

并在主要活动中执行此操作：

    @OnClick(R2.id.btnSearch)
public void onSearchClicked(View view) {

    WeatherApiRequest.getWeatherForecast("en", "hello", new Callback<WeatherForecast>() {


        @Override
        public void onResponse(Call<WeatherForecast> call, Response<WeatherForecast> response) {

            if (response.isSuccessful()) {

                WeatherForecast weatherForecast = response.body();
                StringBuilder builder = new StringBuilder();
                builder.append(weatherForecast.getProvider() + "\n");

                Toast.makeText(MainActivity.this, "response code : " + response.code() + " Provider = " + builder, Toast.LENGTH_SHORT).show();

//

                Timber.i(builder.toString());
            } else {
                Toast.makeText(MainActivity.this, "Try later ! " + response.code(), Toast.LENGTH_SHORT).show();
            }

        }

        @Override
        public void onFailure(Call<WeatherForecast> call, Throwable t) {
            Toast.makeText(MainActivity.this, "Internet might not have been initialized !", Toast.LENGTH_SHORT).show();
        }

    });