How to keep stale file around?

## 💬 Questions and Help

Hi there

I'm wanting to keep stale image files around so that, if the user is offline, the stale one is served rather than checking for a new one and then showing nothing (cause offline).

Obviously, if `maxNrOfCacheObjects` is exceeded then I would expect to see some files be removed, so this question assumes we're within the limit.

How best to achieve this?

Cheers

Tobin

未识别出任何文件、测试或入口点；请先在此 Dart/Flutter 仓库中定位缓存检索和过期文件处理的入口点。该 issue 未定义 Done 的标准，因此请确认现有配置是否能够在离线时提供过期文件，或者是否需要修改文档或代码。

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