Fix: Ignore Authentitcation Context in Response (coscine/issues#2169)

src/STS/Startup.cs

@@ -98,6 +98,9 @@ namespace Coscine.Api.STS
              
                     options.SPOptions.ServiceCertificates.Add(x509Certificate2);
                     options.SPOptions.WantAssertionsSigned = true;
+
+                    // For dealing with `'DeclarationReference' must be an absolute Uri``
+                    options.SPOptions.Compatibility.IgnoreAuthenticationContextInResponse = true;
                 });
         }
     }