Hibernate jpamodel generator is always UP-TO-DATE

I’ve created this script.
As you can see, I’d like to generate JPA metamodel classes of my JPA entities.

As you can see I’ve created a ‘jpamodelgen’, and I’ve assigned to it a sourceSet.

Obviouly, I’ve created a task in order to perform the processor. However, when I perform it, it’s always on UP-TO-DATE state, and it doesn’t generates me nothing.

Waht am I doing wrong?
I’ll appreciate a LOT your help.
Thanks for all.