mapdev\FacebookMessenger\Messages\ActionMessage::toArray PHP Method

    public function toArray()
    {
        $this->checkRecipient();
        if (is_null($this->action)) {
            throw CouldNotCreateMessage::noActionDefined();
        }
        return ['recipient' => ['id' => $this->recipient_id], 'sender_action' => $this->action];
        //return array
        //check null action
    }