HashPayload computes the hash of payload's body according to the webhook's secret token see https://developer.github.com/webhooks/securing/#validating-payloads-from-github returning the hash as a hexadecimal string.

IsValidPayload checks if the github payload's hash fits with the hash computed by GitHub sent as a header.

实例化对象 不管实例多少次，对象就创建一次。.

repo info.