RFR: JDK-8283668: Update IllegalFormatException to use sealed classes

[Alan Bateman]

On 25/03/2022 09:37, Bernd Eckenfels wrote:
> I wonder should the CSR not describe what’s the advantage of this change is and what the compatibility problems are and why they don’t apply here? Especially given the fact that the specific sub exceptions are not sealed I wonder if the risk of breaking existing code is worth it? (But I do see the beauty of such a construct for new code!)
IllegalFormatException does not have any accessible constructors so 
can't extended by classes outside of the java.util packages. So I think 
the only compatibility risk is doing something off label with 
deserialization to create sub-classes.

-Alan