curl -L -X POST 'https://apis.roblox.com/cloud/v2/users/{user}/notifications' \
  -H 'x-api-key: {your-api-key}' \
  -H 'Content-Type: application/json' \
  -d  \
  '{
  "source": {
    "universe": "universes/96623001"
  },
  "payload": {
    "type": "TYPE_UNSPECIFIED",
    "messageId": "5dd7024b-68e3-ac4d-8232-4217f86ca244",
    "parameters": {
      "key": {
        "stringValue": "bronze egg"
      }
    },
    "joinExperience": {
      "launchData": "Launch Data"
    },
    "analyticsData": {
      "category": "Bronze egg hatched"
    }
  }
}'

{
  "path": "users/1/notifications/a6746f2e-2cc6-11ee-be56-0242ac120002",
  "id": "a6746f2e-2cc6-11ee-be56-0242ac120002"
}