Read-only wrapper for Jena Model

[Zak Mc Kracken]

Hi all,

I have a little RDF file (describing a dataset metadata), which I want 
to read in an helper class and return as a read-only view on the file. 
The reason to return it as read-only is that I also keep a simple cache 
of uri/Object, which is a simplified view of RDF resources in the file, 
so a modifiable Model would make it impossible to keep the two aligned.

That said, I wonder if there is some read-only wrapper for the Jena's 
Model interface, something similar to Collections.unmodifiableXXX(), 
which of course, would be based on the decorator pattern, with 
delegation to a base Model for most of the interface methods, except 
interceptors for addXXX(), which would throw 
UnsupportedOperationException. Would be easy to implement it, but I 
don't like to reinvent wheels, if something like that already exists.

Thanks,
Marco.