code: func endpointDifferent(before, after Endpoint) bool {
  	endpoint := before
  	endpoint.ModificationTag = after.ModificationTag
  	endpoint.Presence = after.Presence
  	endpoint.Since = after.Since
  	return endpoint != after
  }
docs: // endpoints are different if any field is different other than the following:
  // 1. ModificationTag
  // 2. Presence
  // 3. Since