chore: Return explict None type for DELETE endpoints

The HTTP response code will become 204 No Content instead of 200. PiperOrigin-RevId: 796123628

Author: DeanChensj

src/google/adk/cli/adk_web_server.py

@@ -457,6 +457,14 @@ async def create_session(
  logger.info("New session created")
  return session
 
+ @app.delete("/apps/{app_name}/users/{user_id}/sessions/{session_id}")
+ async def delete_session(
+ app_name: str, user_id: str, session_id: str
+ ) -> None:
+ await self.session_service.delete_session(
+ app_name=app_name, user_id=user_id, session_id=session_id
+ )
+
  @app.post(
  "/apps/{app_name}/eval_sets/{eval_set_id}",
  response_model_exclude_none=True,
@@ -606,7 +614,9 @@ async def update_eval(
  "/apps/{app_name}/eval_sets/{eval_set_id}/evals/{eval_case_id}",
  tags=[TAG_EVALUATION],
  )
- async def delete_eval(app_name: str, eval_set_id: str, eval_case_id: str):
+ async def delete_eval(
+ app_name: str, eval_set_id: str, eval_case_id: str
+ ) -> None:
  try:
  self.eval_sets_manager.delete_eval_case(
  app_name, eval_set_id, eval_case_id
@@ -733,12 +743,6 @@ async def list_eval_metrics(app_name: str) -> list[MetricInfo]:
  status_code=400, detail=MISSING_EVAL_DEPENDENCIES_MESSAGE
  ) from e
 
- @app.delete("/apps/{app_name}/users/{user_id}/sessions/{session_id}")
- async def delete_session(app_name: str, user_id: str, session_id: str):
- await self.session_service.delete_session(
- app_name=app_name, user_id=user_id, session_id=session_id
- )
-
  @app.get(
  "/apps/{app_name}/users/{user_id}/sessions/{session_id}/artifacts/{artifact_name}",
  response_model_exclude_none=True,
@@ -813,7 +817,7 @@ async def list_artifact_versions(
  )
  async def delete_artifact(
  app_name: str, user_id: str, session_id: str, artifact_name: str
- ):
+ ) -> None:
  await self.artifact_service.delete_artifact(
  app_name=app_name,
  user_id=user_id,