add version of eventcontext without state group

synapse/events/snapshot.py

@@ -114,6 +114,25 @@ class EventContext:
             partial_state=partial_state,
         )
 
+    @staticmethod
+    def without_state_group(
+        storage: "StorageControllers",
+        state_group_before_event: Optional[int],
+        state_delta_due_to_event: Optional[StateMap[str]],
+        partial_state: bool,
+        prev_group: Optional[int] = None,
+        delta_ids: Optional[StateMap[str]] = None,
+    ) -> "EventContext":
+        return EventContext(
+            storage=storage,
+            state_group=None,
+            state_group_before_event=state_group_before_event,
+            state_delta_due_to_event=state_delta_due_to_event,
+            prev_group=prev_group,
+            delta_ids=delta_ids,
+            partial_state=partial_state,
+        )
+
     @staticmethod
     def for_outlier(
         storage: "StorageControllers",