Investigate JEP 409: Sealed Classes

[tgodzik]

JEP 409 introduced sealed classes which in concept are similar to case classes (though obviously implementation is quite different). Since we are planning to update to a newer JDK at an unspecified future I hope we can figure out if this is in any way useful to use for example for some bytecode optimization similar to #22249

And if we can actually use them or whether it will be impossible for us. This might be binary incompatible, but it would be good to see if maybe we can use this to our advantage in some way without sacrificing binary compatibility

Introduced in JDK 17