// POST api/todoapi
        // Saves in the db a new Todo item associated to the current caller
        public void Post(Todo todo)
        {
            VerifyScope();

            todo.Owner = ClaimsPrincipal.Current.FindFirst(ClaimTypes.NameIdentifier).Value;
            db.Todoes.Add(todo);
            db.SaveChanges();
        }
        public void Onboard([FromBody] string name)
        {
            // here "name" is just a placeholder for the real data your app would require from the caller
            // if (MyCustomOnboardingDataValidation(name))
            string upn      = ClaimsPrincipal.Current.FindFirst(ClaimTypes.Name).Value;
            string tenantID = ClaimsPrincipal.Current.FindFirst("http://schemas.microsoft.com/identity/claims/tenantid").Value;

            if (db.Users.FirstOrDefault(a => (a.UPN == upn) && (a.TenantID == tenantID)) == null)
            {
                // add the caller to the collection of valid users
                db.Users.Add(new User {
                    UPN = upn, TenantID = tenantID
                });
            }
            db.SaveChanges();
        }