PermissionAttachment getSource() {
        return this.source;
    }
Injects a fake 'permissions' map into the superclass, for (clever/dumb??) plugins
which attempt to modify attachment permissions using reflection to get around the slow nukkit
behaviour in the base PermissionAttachment implementation.

The fake map proxies calls back to the methods on this attachment
nukkit/src/main/java/me/lucko/luckperms/nukkit/inject/permissible/LuckPermsPermissionAttachment.java