I noticed that `iot:RegisterCertificate` always has `Principal` set to `Unknown`

[nitrocode]

I believe it's due the userIdentity.type which is unknown

{
  "eventVersion": "1.09",
  "userIdentity": {
    "type": "Unknown",
    "principal": "<odd string>"
  },
  "userAgent": "Coral/Netty4",
  "_": "..."
}

This particular event comes up a lot. I wonder if it's better to ignore iot:RegisterCertificate.

I see that the useragent does match for it but it doesn't appear to be clickops to me.

terraform-aws-clickops-notifier/clickopsnotifier/clickops.py

Line 93 in be9694c

self.USER_AGENTS = {"console.amazonaws.com", "Coral/Jakarta", "Coral/Netty4"}