mutation webhookSubscriptionCreate($topic: WebhookSubscriptionTopic!, $webhookSubscription: WebhookSubscriptionInput!) {
  webhookSubscriptionCreate(
    topic: $topic
    webhookSubscription: $webhookSubscription
  ) {
    userErrors {
      field
      message
    }
    webhookSubscription {
      id
      topic
      format
      endpoint {
        __typename
        ... on WebhookHttpEndpoint {
          callbackUrl
        }
      }
    }
  }
}