Cache and Offline Cache in Retrofit2

CacheClientRetrofit2.kt

    private val clientBuilder: OkHttpClient.Builder =
            OkHttpClient.Builder()
                    .addNetworkInterceptor(CacheInterceptor)
                    .addInterceptor(CommonHeaderInterceptor)
                    .cache(cache)
    
    private val retrofitBuilder: Retrofit.Builder =
            Retrofit.Builder()
                    .baseUrl(BASE_URL)
                    .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                    .addConverterFactory(GsonConverterFactory.create(gson))
                    .client(clientBuilder.build())

CacheInterceptor.kt

object CacheInterceptor : Interceptor {
    override fun intercept(chain: Interceptor.Chain): okhttp3.Response {
        var request = chain.request()
        if (!ApiManager.isNetworkAvailable()) {
            request = request.newBuilder()
                    .removeHeader("Pragma")
                    .cacheControl(CacheControl.FORCE_CACHE)
                    .build()
        }

        val originalResponse = chain.proceed(request)
        val cacheControl = originalResponse.header("Cache-Control")

        if (isRemoteNoCache(cacheControl)) {
            return originalResponse.newBuilder()
                    .removeHeader("Pragma")
                    .header("Cache-Control", "public, max-age=" + 5000)
                    .build()
        } else
            return originalResponse
    }

    private fun isRemoteNoCache(cacheControl: String?): Boolean =
            cacheControl == null ||
                    cacheControl.contains("no-store", true) ||
                    cacheControl.contains("no-cache", true) ||
                    cacheControl.contains("must-revalidate", true) ||
                    cacheControl.contains("max-age=0", true)

}

Remember to remove the Pragma header, or you will get 504 code ERROR