Possible CodeReviewThreadTypes of Azure Devops Git Api Threads

I was unable to find anywhere on the internet what the accepted CodeReviewThreadType values were in the Azure DevOps Thread API.I am trying to make our remote service add a system message like "Pull Request successfully linked with XY." and don't want to spam it with huge comments.

I tried abusing some of the types that I usually see in pullrequests - StatusUpdate, RefUpdate, ReviewersUpdate, IsDraftUpdate... but they seem to be translated so the "content" of the comment is ignored and the message stays empty.

Does anyone have any experience with this? I don't need all supported types, just one that gives the desired output.

Desired output with example of content being ignored:

Code sample:

await gitApi.createThread({    comments: [        {            parentCommentId: 0,            content: "System Comment Test",            commentType: CommentType.System,        },    ],    properties: {        CodeReviewThreadType: {"$type": "System.String","$value": "StatusUpdate"        },    },}, (pr.repository!).id!, pr.pullRequestId!);