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kotlinlang

Hi, I’m currently upgrading my project to ktor2.
I use [`CachingHeader` plugin](<https://ktor.io/docs/caching.html>),  and `CachingOptions` (io.ktor.server.http.content) class shows compile errors because it became to need `expires` parameter (non nullable).
As I know, If we want to return `Cache-Control: no-cache` as http response, then `expires` header is not required.
Why is this parameter required?

As I can see, the `expires`  parameter is nullable with a default `null` value in Ktor 2.0.2:
```public data class CachingOptions(val cacheControl: CacheControl? = null, val expires: GMTDate? = null)```
So I can write a code like this:
```install(CachingHeaders) {
    options { call, outgoingContent -&gt;
        CachingOptions(CacheControl.NoCache(CacheControl.Visibility.Public))
    }
}```

Oh, I used io.ktor.server.http.content.CachingOptions, but I replaces it with  io.ktor.http.content.CachingOptions so it works well.
You made me aware of it.
Thank you.