Open is Open.

Open is Open.

Ah, right. Yes, that is quite restrictive at first reading. Reasonably sure there are good legal reasons for that. The most obvious perhaps being the difficulty of determining at what point transformations of a work cross from derived to original. That'd be a huge grey area to get into, both for Sun, for contributors to the CDDL and for users.

From a practical POV, it's maybe not quite as restrictive as it may seem. Note that the grant extends to the Original Software and portions thereof, so you may (by my Joe Bloggs, IANAL, ordinary member of the public reading) strip down the Original Software and use the portion you want, under the terms of the CDDL and that grant. Functional, non-expressive modifications might still be allowed, as they don't affect copyright at least - however I'm uncertain if that extends both ways (ie an author can snarf such modifications at will, does it go the other way? I don't know).

Ie, my inclination would be to apply Occam's razor and take the view that its phrased as it is so as to provide clarity as to the exact reach of the patent grants, rather than as some sinister plot by Sun to sue people for patent breaches. I honestly don't think Sun are interested in suing people for modifying CDDL code as long as they honour the CDDL. Nor do Sun have any track record of patent litigation (well, other than being threatened or sued ;) ).

You might want to bring this up on the CAB-Discuss, might be good to explore it there further, to see what the intent was with that clause and whether or not, if the language does not properly reflect the intent, it would be possible to modify it in a future version of the licence.