Update TrustChainManager.cs

src/Spid.Cie.OIDC.AspNetCore/Services/TrustChainManager.cs

@@ -75,7 +75,7 @@
                     DateTimeOffset expiresOn = opConf.ExpiresOn;
 
                     bool opValidated = false;
-                    foreach (var authorityHint in opConf.AuthorityHints)
+                    foreach (var authorityHint in opConf.AuthorityHints ?? new())
                     {
                         trustChain.Clear();
 
@@ -117,9 +117,9 @@
                                     opConf!.Metadata!.OpenIdProvider.JsonWebKeySet = JsonConvert.DeserializeObject<JsonWebKeySet>(keys);
                                 }
                             }
                             else if (!string.IsNullOrWhiteSpace(JObject.Parse(decodedOPJwt)["metadata"]["openid_provider"]["jwks"].ToString()))
                             {
                                 opConf!.Metadata!.OpenIdProvider.JsonWebKeySet = JsonWebKeySet.Create(JObject.Parse(decodedOPJwt)["metadata"]["openid_provider"]["jwks"].ToString());
                             }
                             if (opConf!.Metadata!.OpenIdProvider.JsonWebKeySet is null)
                             {
@@ -178,7 +178,7 @@
         {
             Throw<Exception>.If(string.IsNullOrWhiteSpace(url), "Url parameter is not defined");
 
             var metadataAddress = $"{url.EnsureTrailingSlash()!}{SpidCieConst.EntityConfigurationPath}";
             var jwt = await _httpClient.GetStringAsync(metadataAddress);
             Throw<Exception>.If(string.IsNullOrWhiteSpace(jwt), $"EntityConfiguration JWT not retrieved from url {metadataAddress}");
 
@@ -194,7 +194,7 @@
             Throw<Exception>.If(string.IsNullOrWhiteSpace(decodedJwtHeader), $"Invalid EntityConfiguration JWT Header for url {metadataAddress}: {jwt}");
 
             var header = JObject.Parse(decodedJwtHeader);
             var kid = (string)header[SpidCieConst.Kid];
             Throw<Exception>.If(string.IsNullOrWhiteSpace(kid), $"No Kid specified in the EntityConfiguration JWT Header for url {metadataAddress}: {decodedJwtHeader}");
 
             var key = conf!.JWKS.Keys.FirstOrDefault(k => k.kid.Equals(kid, StringComparison.InvariantCultureIgnoreCase));