adapter.xml: Fix deserialization for Extension

Currently, the XML deserialization missed the
`<aas:refersTo>` wrapper around the single references
inside `Extension.refers_to`. This commit fixes that.

Author: s-heppner

basyx/aas/adapter/xml/xml_deserialization.py

@@ -692,8 +692,10 @@ def construct_extension(cls, element: etree.Element, object_class=model.Extensio
         value = _get_text_or_none(element.find(NS_AAS + "value"))
         if value is not None:
             extension.value = model.datatypes.from_xsd(value, extension.value_type)
-        extension.refers_to = _failsafe_construct_multiple(element.findall(NS_AAS + "refersTo"),
-                                                           cls._construct_referable_reference, cls.failsafe)
+        extension.refers_to = _failsafe_construct_multiple(
+            element.find(NS_AAS + "refersTo").findall(NS_AAS + "reference"),
+            cls._construct_referable_reference, cls.failsafe
+        )
         cls._amend_abstract_attributes(extension, element)
         return extension
 

test/compliance_tool/files/test_demo_full_example_wrong_attribute.xml

@@ -347,13 +347,15 @@
               <aas:valueType>xs:string</aas:valueType>
               <aas:value>ExampleExtensionValue</aas:value>
               <aas:refersTo>
+                <aas:reference>
                 <aas:type>ModelReference</aas:type>
-                <aas:keys>
-                  <aas:key>
-                    <aas:type>AssetAdministrationShell</aas:type>
-                    <aas:value>http://acplt.org/RefersTo/ExampleRefersTo</aas:value>
-                  </aas:key>
-                </aas:keys>
+                  <aas:keys>
+                    <aas:key>
+                      <aas:type>AssetAdministrationShell</aas:type>
+                      <aas:value>http://acplt.org/RefersTo/ExampleRefersTo</aas:value>
+                    </aas:key>
+                  </aas:keys>
+                </aas:reference>
               </aas:refersTo>
             </aas:extension>
           </aas:extensions>