public async Task <ActionResult <MindMap> > PostMindMap(MindMapDTO mindMap)
        {
            var room = await _roomRepository.Get(mindMap.RoomId);

            if (room == null)
            {
                return(BadRequest());
            }

            var doc = new MindMap
            {
                DateOfCreation = DateTime.UtcNow,
                Name           = mindMap.Name,
                Room           = room,
            };

            await _repository.Add(doc);

            return(Ok()); //  CreatedAtAction("GetChat", new { id = mindMap.Id }, mindMap);
        }