public Task <IdentityUser> FindAsync(UserLoginInfo login) { if (login == null) { throw new ArgumentNullException("login"); } IdentityUser identityUser = null; var byProviderAndKey = _externalLoginRepository.GetByProviderAndKey(login.LoginProvider, login.ProviderKey); if (byProviderAndKey != null) { identityUser = GetIdentityUser(byProviderAndKey.User); } return(Task.FromResult(identityUser)); }