fix: satisfy eval grounding typing

Author: he-yufeng

src/google/adk/evaluation/evaluation_generator.py

@@ -626,7 +626,7 @@ def convert_events_to_eval_invocations(
     invocations = []
     for invocation_id, events in events_by_invocation_id.items():
       final_response = None
-      final_event = None
+      final_event: Optional[Event] = None
       user_content = Content(parts=[])
       invocation_timestamp = 0
       app_details = None
@@ -636,7 +636,7 @@ def convert_events_to_eval_invocations(
       ):
         app_details = app_details_per_invocation[invocation_id]
 
-      events_to_add = []
+      events_to_add: list[Event] = []
 
       for event in events:
         current_author = (event.author or _DEFAULT_AUTHOR).lower()
@@ -670,7 +670,11 @@ def convert_events_to_eval_invocations(
 
       invocation_events = []
       for e in events_to_add:
-        if e is final_event and not e.grounding_metadata:
+        if (
+            final_event is not None
+            and e is final_event
+            and not e.grounding_metadata
+        ):
           continue
         invocation_events.append(
             InvocationEvent(

src/google/adk/evaluation/llm_as_judge_utils.py

@@ -17,6 +17,7 @@
 import enum
 import statistics
 from typing import Any
+from typing import cast
 from typing import Optional
 from typing import Union
 
@@ -224,11 +225,14 @@ def get_grounding_metadata_as_json_str(
   if not grounding_metadata:
     return "No grounding metadata was provided."
 
-  return _GroundingMetadataEntries(
-      grounding_metadata=grounding_metadata
-  ).model_dump_json(
-      indent=2,
-      exclude_unset=True,
-      exclude_defaults=True,
-      exclude_none=True,
+  return cast(
+      str,
+      _GroundingMetadataEntries(
+          grounding_metadata=grounding_metadata
+      ).model_dump_json(
+          indent=2,
+          exclude_unset=True,
+          exclude_defaults=True,
+          exclude_none=True,
+      ),
   )