CreateMilestoneLevelBody

{
    "title": "Gold Level",
    "levelNumber": 32,
    "rewards": {
        "rewardIds": [
            "123e4567-e89b-12d3-a456-426655440000"
        ],
        "collectionIds": [
            "123e4567-e89b-12d3-a456-426655440000"
        ]
    }
}