channelId

Opaque Android notification-channel identifier from FCM data key _ci.

This value is case-sensitive and preserved exactly as received, including empty strings and whitespace. The SDK does not validate or normalize the value and never creates a android.app.NotificationChannel for it.

When no NotificationManager.NotificationChannelIdProvider is configured, the Push Feature Module looks up this exact ID with android.app.NotificationManager.getNotificationChannel and uses it only if that channel already exists. Missing channels and lookup failures fall back to the SDK default channel.

When a provider is configured, this value is available for inspection only; the provider owns channel selection and the SDK does not automatically select this ID.

null means the payload omitted _ci.