title: (FB Instant games) How I can get payload data from Game Play Button?
body: <p>According to this article: <a href="https://developers.facebook.com/docs/messenger-platform/reference/buttons/game-play/" rel="nofollow noreferrer">https://developers.facebook.com/docs/messenger-platform/reference/buttons/game-play/</a> I can post parameter "payload" for button with "SERIALIZED_JSON_PAYLOAD" and "this data will be sent to the game". How I can receive this data inside my game?</p>