This would be useful if it was used in some places where passing a null is illegal (instead of manually checking inside the method). On one hand, code that would be annotated thus would already specify that null values are illegal , and throw a exception if passed them.
On the other hand the programmer that uses that code correctly nowadays structures is code so that the variable can't be null. But the checker framework can't know that right? So marking code that way would percolate up like a domino chain (making transition a nightmare). So i guess that answers the case of the existing code. Would sun consider to make any new code use those annotations ?
