public void SeedRoleAsync()
        {
            var roles = new IdentityRole[] { new IdentityRole(nameof(UserRole.Anonymous))
                                             , new IdentityRole(nameof(UserRole.NormalUser))
                                             , new IdentityRole(nameof(UserRole.CustomerAdmin))
                                             , new IdentityRole(nameof(UserRole.TenantAdmin))
                                             , new IdentityRole(nameof(UserRole.SystemAdmin)) };

            roles.ToList().ForEach(async role =>
            {
                await _role.CreateAsync(role).ContinueWith(async ir =>
                {
                    if (ir.Result.Succeeded)
                    {
                        await _role.UpdateNormalizedRoleNameAsync(role);
                    }
                });
            });
            _context.SaveChanges();
        }