Sign in with google into firebase using the new Credential Manager API

I'm learning Kotlin/Compose by making a to-do app with Firebase. Right now I'm trying to add Google sign-in. At first, I had been following a YouTube tutorial, but the API it was using turned out to be deprecated. I checked the official Firebase docs, but they are also outdated. So I'm trying to work it out on my own.

The deprecation message says I need to use Credential Manager. So far, I've managed to show the Google dialog and receive a GetCredentialResponse. The next step, I suppose, is to call Firebase.auth.signInWithCredential(<credentials>), but it needs an AuthCredential object, while I have a completely different type. There seems to be no way to create an AuthCredential object on my own - the initializer is package-private. What am I supposed to do?

My code

val googleIdOption = GetGoogleIdOption.Builder()
    .setAutoSelectEnabled(false)
    .setFilterByAuthorizedAccounts(false)
    .setServerClientId("...")
    .build()


val request = GetCredentialRequest.Builder()
    .addCredentialOption(googleIdOption)
    .build()

val result = try {
    credentialManager.getCredential(request = request, context = context)
} catch (e: Exception) {
    e.printStackTrace()
    if (e is kotlin.coroutines.cancellation.CancellationException) throw e
    null
}


val user = Firebase.auth.signInWithCredential(???).await()

Update: I found the GoogleAuthProvider.getCredential() method that creates an AuthCredential from the provided id token. Technically, I can now extract the idToken from the response bundle, but that would require manually parsing it. This seems wrong. Is there really no built in method?

Found the method that parses the credential response: GoogleIdTokenCredential.createFrom(result.credential.data).

Full code:

val credential = result?.credential
val authCredential =
    if (credential is CustomCredential && credential.type == GoogleIdTokenCredential.TYPE_GOOGLE_ID_TOKEN_CREDENTIAL) {
        val googleIdTokenCredential =
            GoogleIdTokenCredential.createFrom(credential.data)

        GoogleAuthProvider.getCredential(googleIdTokenCredential.idToken, null)
    } else {
        throw RuntimeException("Received an invalid credential type")
    }

Firebase.auth.signInWithCredential(authCredential).await()