public static SyncPlayerInventoryGuidMessage Send(
        GameObject recipient, List <InventorySlot> slots)
    {
        var slotsCollection = new SyncPlayerInventoryList(slots);
        SyncPlayerInventoryGuidMessage msg = new SyncPlayerInventoryGuidMessage
        {
            Recipient = recipient.GetComponent <NetworkIdentity>().netId,            //?
            Data      = JsonUtility.ToJson(slotsCollection),
        };

        msg.SendTo(recipient);
        return(msg);
    }