StartOverIntentHandler.kt

class StartOverIntentHandler : RequestHandler {

    override fun canHandle(input: HandlerInput) =
        input.matches(Predicates.intentName("AMAZON.StartOverIntent"))

    override fun handle(input: HandlerInput): Optional<Response> {
        return input.attributesManager.persistentAttributes["lastPlayedAudio"]?.let {
            input.playAudio(it.toAudio().url)
        } ?: input.emptyResponse()
    }

    private fun HandlerInput.playAudio(audioUrl: String) = responseBuilder
        .addAudioPlayerPlayDirective(
            PlayBehavior.REPLACE_ALL,
            0L,
            null,
            "token",
            audioUrl
        )
        .build()
}