offline-interceptor.kt

static Interceptor offlineInterceptor= new Interceptor() {
   @Override
    public okhttp3.Response intercept(Chain chain) throws IOException {
    Request request = chain.request();
    if (!isInternetAvailable()) {
        int maxStale = 60 * 60 * 24 * 30; // Offline cache available for 30 days 
        request = request.newBuilder()
                .header("Cache-Control", "public, only-if-cached, max-stale=" + maxStale)
                .removeHeader("Pragma")
                .build();
      }
      return chain.proceed(request);
   }
 };