session情報の一部がnullとなる

[morizooo]

{
    "id": "0c6a6ef2-3154-4791-8265-e21b5fc0c499",
    "conference_id": "4c343491-dcd2-45aa-9937-0cbd206383ee",
    "room_id": "",
    "speaker_id": "61af27d8-372b-4d28-ac73-ecb0b7a165fa",
    "title": "How To Drink water",
    "abstract": "oishii",
    "memo": "",
    "starts_on": "0001-01-01T00:00:00Z",
    "duration": 60,
    "material_level": "beginner",
    "spoken_language": "en",
    "slide_language": "en",
    "slide_subtitles": "en",
    "photo_permission": "allow",
    "video_permission": "allow",
    "has_interpretation": false,
    "status": "pending",
    "confirmed": false,
    "conference": null,
    "room": null,
    "speaker": null
  }

"conference": null,
"room": null,
"speaker": null
で返ってきます。