public async Task <CreateMessageGroup> Handle(CreateMessageGroup request, CancellationToken cancellationToken) { var messageGroup = _mapper.Map <MessageGroup>(request); bool hasGroup = await _chatManager.HasMessageGroup(messageGroup.SenderId, messageGroup.ReceiverId); if (hasGroup) { return(null); } var result = await _chatManager.CreateNewGroup(messageGroup); var group = _mapper.Map <CreateMessageGroup>(result); return(group); }