ignoring return value of 'bool std::unordered_map<_Key, _Tp, _Hash, _Pred, _Alloc>::empty() const [with _Key = Hedera::TokenId; _Tp = std::vector<Hedera::TokenNftTransfer>; _Hash = std::hash<Hedera::TokenId>; _Pred = std::equal_to<Hedera::TokenId>; _Alloc = std::allocator<std::pair<const Hedera::TokenId, std::vector<Hedera::TokenNftTransfer> > >]', declared with attribute 'nodiscard' [-Wunused-result]