public static OkHttpClient defaultClient(String token, Duration timeout) {
        return new OkHttpClient.Builder()
                .addInterceptor(new AuthenticationInterceptor(token))
                .connectionPool(new ConnectionPool(5, 1, TimeUnit.SECONDS))
                .readTimeout(timeout.toMillis(), TimeUnit.MILLISECONDS)
                .build();
    }
Shuts down the OkHttp ExecutorService.
The default behaviour of OkHttp's ExecutorService (ConnectionPool)
is to shut down after an idle timeout of 60s.
Call this method to shut down the ExecutorService immediately.
service/src/main/java/com/theokanning/openai/service/OpenAiService.java