@Override
        public boolean remove(Object o) {
            removeAttachment((PermissionAttachment) o);
            return true;
        }
A fake set to be injected into the superclass. This implementation simply
proxies calls back to this permissible instance.

Some (clever/dumb??) plugins attempt to add/remove/query attachments using reflection.

An instance of this map is injected into the super instance so these plugins continue
to work with LuckPerms.
nukkit/src/main/java/me/lucko/luckperms/nukkit/inject/permissible/LuckPermsPermissible.java