public async Task <int> Handle(CreateProposalCommand request, CancellationToken cancellationToken)
        {
            var proposal = new Proposal(request.Countries);

            proposal.SetGeneralProperties(request.Name, request.ClientName, request.Comments);
            _context.Proposals.Add(proposal);
            await _context.SaveChangesAsync(cancellationToken);

            return(proposal.Id);
        }