I have a form with three levels of nesting. Imagine a group, which has users, which have phone numbers.
The GroupType has the option cascade_validation => true, and a collection of UserType.
The UserType has the option cascade_validation => true, and a collection of PhoneType.

I have validations defined for the three entities in the file validation.yml, simple NotBlank validations.
The validations of Group and User work perfectly and I get the error when I try to submit the form with blank fields, but if I let the fields of the Phone empty, the form goes ahead and causes a db error because is receiving a null for a non null column.

The issue is in beta4, I haven't had time to test it in the RC1, even I haven't seen anything related in the change log.