In Java SWIG, any method that returns a non-zero int throws a WiredTigerException, but that exception is not in the method signature.

I think this is the needed SWIG, which could be macro-ized:

%javaexception("com.wiredtiger.db.WiredTigerException")
     __wt_connection::some_function { $action; }

There will undoubtedly be some fallout with the few Java tests we have to accommodate the exceptions.