Implicit constructor of the super class of a null restricted value class

[Remi Forax]

Hello,
I had a little more time to re-read the different specs :)

In https://bugs.openjdk.org/browse/JDK-8317765, 
an implicit constructor must be public and the super class is either Object or a super class with an implicit constructor.

This means that we can NOT create a null restricted value record because the constructor of Record is protected.

I think the constraints on the implicit constructor of the super class should be relaxed. The implicit constructor of the super class does not have to be public.

The implicit constructor of a super class just has to be visible from the implicit constructor of the value class like if there was a super() call inside the implicit constructor of the value class.

regards,
Rémi