Mark the filter_id in the response of POST /filter as required
@@ -91,7 +91,12 @@ paths:
filter_id:
type: string
description: |-
- The ID of the filter that was created.
+ The ID of the filter that was created. Cannot start
+ with a ``{`` as this character is used to determine
+ if the filter provided is inline JSON or a previously
+ declared filter by homeservers on some APIs.
+ example: "66696p746572"
+ required: ['filter_id']
tags:
- Room participation
"/user/{userId}/filter/{filterId}":
