src/vs/workbench/api/browser/mainThreadComments.ts/MainThreadCommentThread/initialCollapsibleState
class MainThreadCommentThread:	private set initialCollapsibleState(initialCollapsibleState: languages.CommentThreadCollapsibleState | undefined) {
		this._initialCollapsibleState = initialCollapsibleState;
		this._onDidChangeInitialCollapsibleState.fire(initialCollapsibleState);
	}