Initial state of AuthenticationStateProvider

Following the documentation, I created my custom AuthenticationStateProvider as follows:

public class ApiAuthStateProvider : AuthenticationStateProvider
{
    private static AuthenticationState anonymousState = ?

    private AuthenticationState _authState;

    public ApiAuthStateProvider()
    {
        _authState = anonymousState;
    }

    public void SetAuthenticationState(AuthenticationState authState)
    {
        _authState = authState ?? anonymousState;
        NotifyAuthenticationStateChanged(GetAuthenticationStateAsync());
    }

    public override Task<AuthenticationState> GetAuthenticationStateAsync()
    {
        return Task.FromResult(_authState);
    }
}

The issue is how to initialize anonymous state, so that _authState.User.Identity.IsAuthenticated is false. As in the document, the following will result in authenticated user:

private static AuthenticationState anonymousState = 
    new AuthenticationState(new ClaimsPrincipal(
    new ClaimsIdentity(new Claim[] {}, "none")));

Even the following resulted in authenticated user:

public class AnonymousIdentity : IIdentity
{
    public string AuthenticationType => "none";
    public bool IsAuthenticated => false;
    public string Name => string.Empty;
}

private static AuthenticationState anonymousState;

static ApiAuthStateProvider()
{
    var anonymousIdentity = new AnonymousIdentity();
    var user = new ClaimsIdentity(anonymousIdentity);
    anonymousState = new AuthenticationState(
        new ClaimsPrincipal(user));
}

What am I missing here?

Yes, just use:

new AuthenticationState(new ClaimsPrincipal());

This code works for me:

    public class CustomAuthenticationProvider : AuthenticationStateProvider
    {
        private readonly HttpClient _httpClient;
        public CustomAuthenticationProvider(HttpClient httpClient)
        {
            _httpClient = httpClient;
        }
        public override async Task<AuthenticationState>
            GetAuthenticationStateAsync()
        {
            ClaimsPrincipal user;
            // Call the GetUser method to get the status
            // This only sets things like the AuthorizeView
            // and the AuthenticationState CascadingParameter
            var result =
                await _httpClient.GetJsonAsync<BlazorUser>("api/user/GetUser");
            // Was a UserName returned?
            if (result.UserName != "")
            {
                // Create a ClaimsPrincipal for the user
                var identity = new ClaimsIdentity(new[]
                {
                   new Claim(ClaimTypes.Name, result.UserName),
                }, "AzureAdAuth");
                user = new ClaimsPrincipal(identity);
            }
            else
            {
                user = new ClaimsPrincipal(); // Not logged in
            }
            return await Task.FromResult(new AuthenticationState(user));
        }
    }

See: Client Side Blazor Authentication Using Azure AD and a Custom AuthenticationStateProvider