Add type annotations to `synapse.metrics` (#10847)

1 files changed, 3 insertions, 1 deletions

diff --git a/synapse/groups/attestations.py b/synapse/groups/attestations.py

index 53f99031b1..a87896e538 100644
--- a/synapse/groups/attestations.py
+++ b/synapse/groups/attestations.py
@@ -40,6 +40,8 @@ from typing import TYPE_CHECKING, Optional, Tuple
 
 from signedjson.sign import sign_json
 
+from twisted.internet.defer import Deferred
+
 from synapse.api.errors import HttpResponseException, RequestSendFailed, SynapseError
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.types import JsonDict, get_domain_from_id
@@ -166,7 +168,7 @@ class GroupAttestionRenewer:
 
         return {}
 
-    def _start_renew_attestations(self) -> None:
+    def _start_renew_attestations(self) -> "Deferred[None]":
         return run_as_background_process("renew_attestations", self._renew_attestations)
 
     async def _renew_attestations(self) -> None: