AggregatedRelations

{
     "m.annotation": {
        "chunk": [
             {
                 "type": "m.reaction",
                 "key": "👍",
                 "count": 3
             }
            ],
            "limited": false,
            "count": 1
     },
     "m.reference": {
         "chunk": [
             {
                "type": "m.room.message",
                "event_id": "$some_event_id"
            }
         ],
         "limited": false,
         "count": 1
         }
    }