Fix: AES-GCM Support

coscine/issues#1715

src/STS/Controllers/ShibbolethController.cs

@@ -43,6 +43,11 @@ namespace Coscine.Api.STS.Controllers
             var externalIdModel = new ExternalIdModel();
             var entity = info.Principal.FindFirstValue(ShibbolethAttributeMapping.Identifier);
 
+            if (string.IsNullOrWhiteSpace(entity))
+            {
+                entity = info.Principal.FindFirstValue(ShibbolethAttributeMapping.PairwiseID);
+            }
+
             var identifier = entity[(entity.IndexOf(">") + 1)..];
             identifier = identifier.Substring(0, identifier.IndexOf("<"));