put https://api.smartrecruiters.com/webhooks-api/v201907/subscriptions//activation
To ensure that the target server is ready to consume notifications, we require you to implement the initial
handshake.
Having subscription with callbackUrl: https://example.org/hook, during activation we will make POST
request with X-Hook-Secret header:
POST https://example.com/hook
X-Hook-Secret: 4jn8fs9011jj8
We expect your server to respond within the time of 20 seconds with HTTP 200 response containing
X-Hook-Secret header with the same value.
Response 200
X-Hook-Secret: 4jn8fs9011jj8