Dagger module that provides a basic Retrofit - Gson - OkHttp - RxJava setup

ApiModule

@Module
public final class ApiModule {
    private static final int OK_HTTP_CACHE_SIZE = 10 * 1024 * 1024;
    private static final String GSON_DATE_FORMAT = "yyyy-MM-dd";

    private String baseUrl;
    private String apiKey;

    public ApiModule(String baseUrl, String apiKey) {
        this.baseUrl = baseUrl;
        this.apiKey = apiKey;
    }

    @Provides
    @Singleton
    Cache providesOkHttpCache(App app) {
        return new Cache(app.getCacheDir(), OK_HTTP_CACHE_SIZE);
    }

    @Provides
    @Singleton
    Gson providesGson() {
        Gson gson = new GsonBuilder()
                .setDateFormat(GSON_DATE_FORMAT)
                .create();

        return gson;
    }

    @Provides
    @Singleton
    Interceptor providesApiKeyInterceptor() {
        final Interceptor apiKeyInterceptor = chain -> {
            HttpUrl url = chain.request().url()
                    .newBuilder()
                    .addQueryParameter("api_key", apiKey)
                    .build();
            Request request = chain.request().newBuilder().url(url).build();
            return chain.proceed(request);
        };

        return apiKeyInterceptor;
    }

    @Provides
    @Singleton
    HttpLoggingInterceptor providesHttpLoggingInterceptor() {
        final HttpLoggingInterceptor httpLoggingInterceptor = new HttpLoggingInterceptor();
        if (BuildConfig.DEBUG) {
            httpLoggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
        } else {
            httpLoggingInterceptor.setLevel(HttpLoggingInterceptor.Level.NONE);
        }
        return httpLoggingInterceptor;
    }

    @Provides
    @Singleton
    OkHttpClient providesOkHttpClient(Cache cache, Interceptor apiKeyInterceptor,
                                      HttpLoggingInterceptor loggingInterceptor) {
        OkHttpClient client = new OkHttpClient.Builder()
                .addInterceptor(apiKeyInterceptor)
                .addInterceptor(loggingInterceptor)
                .cache(cache)
                .build();

        return client;
    }

    @Provides
    @Singleton
    Retrofit providesRetrofit(Gson gson, OkHttpClient client) {
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl(baseUrl)
                .addConverterFactory(GsonConverterFactory.create(gson))
                .addCallAdapterFactory(RxJavaCallAdapterFactory
                        .createWithScheduler(Schedulers.newThread()))
                .client(client)
                .build();

        return retrofit;
    }
    
    @Provides
    @Singleton
    UserService providesMovieService(Retrofit retrofit) {
        return retrofit.create(User.class);
    }
}