Do wildcards exist for Firebase Fuctions on Storage?

I've been using successfully Firebase Functions to perform operations on files I've been uploading to Firebase Storage.

What I currently want to do is access the folder into which I'm shoving data by using wildcards, with the same method of implementation as how it works for the Realtime Database + Firestore. However, whenever I try to access these parameters, they exclusively return null.

Is this not possible?

Here's an example of my code:

  exports.generateThumbnail = functions.storage.object('user-photos/{userId}/{publicOrPrivate}').onChange(event => {
    const privateOrPublic = event.params.publicOrPrivate;
    const isPrivate = (event.params.publicOrPrivate == "private");
    const userId = event.params.userId;

    console.log("user id and publicOrPrivate are", userId, privateOrPublic);
    //"user id and publicOrPrivate are undefined undefined"
    }

Thanks!