public async Task <JwtToken> GetTokenAsync(TokenRequestArgs args)
        {
            //first validate user name and password
            await SignInAsync(args);

            //store refresh token
            var refreshToken = Guid.NewGuid().ToString().Replace("-", string.Empty);
            await _tenantRepository.AddRefreshTokenAsync(new RefreshToken
            {
                ClientID         = args.client_id,
                UserName         = args.username,
                Token            = refreshToken,
                ExpiresInMinutes = expiresInMinutes
            });

            args.refresh_token = refreshToken;
            return(await CreateTokenAsync(args));
        }