Replace logic related to hibernate NotEmpty with new javax.validation.constraints.NotEmpty

[denis-anisimov]

Binder uses some logic which relies on NotEmpty annotation from hibernate.

New validation API contains new annotation javax.validation.constraints.NotEmpty which should be used instead or along with the old hibernate annotation.

Update unit tests.

[pleku]

Currently <artifactId>hibernate-validator</artifactId> is only a test scope dependency for flow-data. I see no usage of it in Binderor BeanValidationBinder.

So is this issue a) totally unnecessary b) about just updating unit tests ? @denis-anisimov

[denis-anisimov]

See com.vaadin.data.RequiredFieldConfigurator. We use FQN to compare the class name.
So we don't need to depend on hibernate. If it's in the classpath then the annotation might be used and it will be checked. If it's not in the classpath then annotation simply can't be used.
Our code works regardless of hibernate presence.

But this annotation is now available in new validation API. It should be used instead/in addition to.