public async Task BroadcastInGroupAsync(byte[] buffer, CustomWebSocket userWebSocket, ICustomWebSocketFactory wsFactory)
{
var others = wsFactory.AllInGroup(userWebSocket);
foreach (var uws in others)
{
await uws.WebSocket.SendAsync(new ArraySegment <byte>(buffer, 0, buffer.Length), WebSocketMessageType.Text, true, CancellationToken.None);
}
}