Issue Summary

users with guest role cant be mentioned in whiteboard but can be searched and mentioned on pages

This is reproducible on Data Center: NA

Steps to Reproduce

1. Invite a guest user if guest user is not already present.
2. Create a whiteboard on same space where guest user has access.
3. Use comment feature to mention guest user

Expected Results

It should search the guest user as soon as @mention entered in comment box.

Actual Results

It does not search guest user

However, same guest user can be searched and mentioned on pages within same space

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available