Logger.java

HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor(); 
interceptor.setLevel(HttpLoggingInterceptor.Level.BASIC); 
OkHttpClient client = new OkHttpClient.Builder().addInterceptor(interceptor).build(); 

Retrofit retrofit = new Retrofit.Builder() 
        .baseUrl(BuildConfig.API_BITCOIN_BASE_URL) 
        .client(client) 
        .addConverterFactory(GsonConverterFactory.create()) 
        .addCallAdapterFactory(RxJavaCallAdapterFactory.create()) 
        .build();