Can a Message Filter Extension specify more than ILMessageFilterExtensionNetworkURL or switch which is used?

I asked this question of AI and it said that yes it was possible, and gave some sample code

override class func filterConfiguration() -> ILMessageFilterExtensionConfiguration {
    let config = ILMessageFilterExtensionConfiguration()
    
    // You can specify multiple network URLs
    config.networkURLs = [
        URL(string: "https://api1.example.com/filter")!,
        URL(string: "https://api2.example.com/filter")!
    ]
    
    return config
}

And said the OS will try the first, and if there's no response within the first few seconds it'll move onto the second.

However, there is no such class as ILMessageFilterExtensionConfiguration AFAICT, if there is then how to access/use it, if there isn't, then I wonder how the AI counjured it up?

If multiple urls can be specified, then can the extension also specify a particular API to use and switch between them at some point?

When does the OS call filterConfiguration()?