Secret field is missing on Repository Hooks API

[Jeremy Kreutzbender]

The documentation on creating Webhooks (https://confluence.atlassian.com/bitbucketserver071/managing-webhooks-in-bitbucket-server-998653697.html#ManagingwebhooksinBitbucketServer-webhooksecretsWebhooksecrets) says that I can 

`6. (optional) Enter a  Secret  string of up to 255 characters.`

When I go to create a Webhook manually I do not see anywhere to input this secret. Additionally the API documentation (https://developer.atlassian.com/bitbucket/api/2/reference/resource/repositories/%7Bworkspace%7D/%7Brepo_slug%7D/hooks#post) does not reference passing in a secret at all either.

I'm curious how I secure my webhoooks. Thank you