# CmcdConfiguration.HeaderKey

# CmcdConfiguration.HeaderKey

Artifact:[androidx.media3:media3-exoplayer](https://developer.android.com/jetpack/androidx/releases/media3)  
[View Source](https://cs.android.com/search?q=file:androidx/media3/exoplayer/upstream/CmcdConfiguration.java+class:androidx.media3.exoplayer.upstream.CmcdConfiguration.HeaderKey)

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Kotlin\|[Java](https://developer.android.com/reference/androidx/media3/exoplayer/upstream/CmcdConfiguration.HeaderKey "View this page in Java")

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```
@Retention(value = RetentionPolicy.SOURCE)
@StringDef(value = )
@Documented
@Target(value = ElementType.TYPE_USE)
annotation CmcdConfiguration.HeaderKey
```

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Header keys SHOULD be allocated to one of the four defined header names based upon their expected level of variability:

- CMCD-Object: keys whose values vary with the object being requested.
- CMCD-Request: keys whose values vary with each request.
- CMCD-Session: keys whose values are expected to be invariant over the life of the session.
- CMCD-Status: keys whose values do not vary with every request or object.