sign_in_callback.kt

private val loginResult =
    registerForActivityResult(ActivityResultContracts.StartIntentSenderForResult()) {
        val credential = oneTapClient.getSignInCredentialFromIntent(it.data)
        val idToken = credential.googleIdToken
        val username = credential.id
        val password = credential.password
        when {
            idToken != null -> {
                // Got an ID token from Google. Use it to authenticate
                // with your backend.
                Log.d(TAG, "Got ID token.")
            }
            password != null -> {
                // Got a saved username and password. Use them to authenticate
                // with your backend.
                Log.d(TAG, "Got password.")
            }
            else -> {
                // Shouldn't happen.
                Log.d(TAG, "No ID token or password!")
            }
        }
    }