private string AddQueryParametersToEndpoint() { var endpointBuilder = new StringBuilder(_endpoint + "?"); if (_queryParams != null) { foreach (var param in _queryParams) { endpointBuilder.Append($"{param.Key}={param.Value}&"); } } endpointBuilder.Append($"timestamp={GetTimestamp()}&nonce={CryptoEngine.GenerateNonce()}"); return(endpointBuilder.ToString()); }