NotepadActivity.kt

val reviewManager = ReviewManagerFactory.create(this)
reviewManager.requestReviewFlow()
    .addOnCompleteListener { task ->
        if (task.isSuccessful) {
            reviewManager.launchReviewFlow(this, task.result)
                .addOnCompleteListener {
                    // Continue the normal user flow.
                }
        } else {
            // Continue the normal user flow.
        }
    }