A new mechanism to ensure that a deserialized field value is not shared,
and loaded by the same loader, or parent of, the object being
constructed’s loader.

This will eliminate the need to define a readObject to essentially copy
the deserialized field value, as it cannot always be trusted. And again
the issue with final fields. Something along the lines of:

   class Foo {
       @Confined
       private final Bar bar = new BarImpl();
   }

@Confined could be placed on fields, or possibly classes.