Fix: Make swagger doc compliant to OpenAPI (#3394)

This fixes issues in the swagger.json file. The motivation to do so is to be able to generate API clients using https://openapi-generator.tech Doing so will require further changes to the api spec, but this seems like a good first step since it is now "valid" according to editor.swagger.io and openapi-generator validate.

Fixes #2806

swagger/paths/application/inboxes/inbox_members/create.yml

@@ -11,15 +11,18 @@ parameters:
     required: true
     schema:
       type: object
+      required:
+          - inbox_id
+          - user_ids
       properties:
         inbox_id:
           type: string
           description: The ID of the inbox
-          required: true
-        user_ids: 
+        user_ids:
           type: array
+          items:
+            type: integer
           description: IDs of users to be added to the inbox
-          required: true
 responses:
   200:
     description: Success