internal TradeOffer(ulong tradeOfferID, uint otherSteamID3, ETradeOfferState state) { if ((tradeOfferID == 0) || (otherSteamID3 == 0) || (state == ETradeOfferState.Unknown)) { throw new ArgumentNullException(nameof(tradeOfferID) + " || " + nameof(otherSteamID3) + " || " + nameof(state)); } TradeOfferID = tradeOfferID; OtherSteamID3 = otherSteamID3; State = state; }