`synchronization/secrets` Cannot remove secret when json is value

Hello! Not sure if this is the best place to report this, but thought I'd give it a shot.

We have noticed an issue with the https://graph.microsoft.com/beta/servicePrincipals/${serviceprincipal}/synchronization/secrets api endpoint.

It only supports GET and PUT, so if you want to remove secrets, you have to perform a PUT with the value of the secret as "".

However, this only works if the original value of the secret was a plain string value.
If the value was a complex type, such as a JSON blob (as in the example here: https://learn.microsoft.com/en-us/graph/api/synchronization-synchronization-secrets?view=graph-rest-beta&tabs=http#request), there does not appear to be a way to remove the secret because if you set the value to an empty "" string, you get the following error:

Bad Request({"error":{"code":"UnknownError","message":"{\r\n  \"error\":{\r\n    \"code\":\"InvalidNotificationSettings\",\"message\":null,\"target\":null,\"details\":[\r\n      \r\n    ],\"innerError\":null\r\n  }\r\n}","innerError":{"date":"2023-01-11T16:57:55","request-id":"8927006e-edb2-435b-a966-49559c4fd064","client-request-id":"8927006e-edb2-435b-a966-49559c4fd064"}}})

We also tried setting the value to "{}", which worked, but leaves the secret in place like below:

{
  "@odata.context": "https://graph.microsoft.com/beta/$metadata#servicePrincipals('123456-12312312-123123-')/synchronization/secrets",
  "value": [
    {
      "key": "SyncNotificationSettings",
      "value": "{}"
    }
  ]
}

Is this an API bug?

Originally posted by @tagur87 in https://github.com/microsoftgraph/msgraph-metadata/issues/127#issuecomment-1379210820

Start with the Microsoft Graph synchronization/secrets endpoint and the linked synchronization-secrets documentation example. Reproduce the PUT behavior for a plain-string secret versus the JSON value, including the empty-string and "{}" cases. Done means establishing whether the API supports deletion for complex values and identifying the appropriate documented or API-level resolution.