Add extra fields to client events unsigned section callbacks
+First introduced in Synapse v1.96.0
+This callback allows modules to add extra fields to the unsigned section of +events when they get sent down to clients.
+These get called every time an event is to be sent to clients, so care should +be taken to ensure with respect to performance.
+API
+To register the callback, use
+register_add_extra_fields_to_unsigned_client_event_callbacks on the
+ModuleApi.
The callback should be of the form
+async def add_field_to_unsigned(
+ event: EventBase,
+) -> JsonDict:
+where the extra fields to add to the event's unsigned section is returned.
+(Modules must not attempt to modify the event directly).
This cannot be used to alter the "core" fields in the unsigned section emitted +by Synapse itself.
+If multiple such callbacks try to add the same field to an event's unsigned +section, the last-registered callback wins.
+ +