{
    "customer": {
        "id": string,
        "externalId": string,
        "email": string,
        "name": string,
        "birthdayMonth": integer,
        "birthdayDay": integer,
        "referralUrl": string,
        "pointBalance": integer,
        "currentLoyaltyTier": {
            "id": string,
            "title": string
        },
        "createdAt": date,
        "updatedAt": date
    },
    "oldTier": {
        "id": string,
        "title": string,
        "threshold": string
    },
    "newTier": {
        "id": string,
        "title": string,
        "threshold": string
    }
}