Webview editors are not registered editors?

While working on https://github.com/microsoft/vscode/issues/131587 I noticed that webview editors such as `mainThreadWebview-markdown.preview` does not appear to be registered in the `IEditorResolverService`. As such, I have to do an ugly hack to still offer this editor for the user to configure: https://github.com/microsoft/vscode/blob/69f8d940e2de132c170240acf665869df9bece3a/src/vs/workbench/browser/parts/editor/editorConfiguration.ts#L19-L29 I am not sure what I can do here, is there an alternative service I can use to figure out the contributed webview editors? Can these custom webview editors register to the editor resolver, maybe in a way that they appear in the registry but cannot be picked by the user?