component AP gateway (http/outbox): return data when no RSM is available

sat/plugins/plugin_comp_ap_gateway/http_server.py

@@ -722,6 +722,10 @@ class HTTPAPGServer(web_resource.Resource):
             "orderedItems": ordered_items
         }
 
+        if "rsm" not in metadata:
+            # no RSM available, we return what we have
+            return ret_data
+
         # AP OrderedCollection must be in reversed chronological order, thus the opposite
         # of what we get with RSM (at least with Libervia Pubsub)
         if not metadata["complete"]: