RFR: JEP 360: Sealed Types (Preview)

Hi all, The sealed types JEP was already reviewed a while back when we were planning to include it in JDK14. It finally fell off that boat but it is being considered now for JDK15. There have been some changes since then mostly related to subtypes of a sealed type. Before we were planning to infer finality, sealness or non-sealness in the subtypes. We steered away from that direction in favor of explicit declaration at the subtype. I would like to ask for another review of the current version of the JEP that reflects these changes. The JEP is at [1] and the last version of the spec is at [2], Thanks, Vicente [1] https://bugs.openjdk.java.net/browse/JDK-8227043 [2] http://cr.openjdk.java.net/~gbierman/jep360/jep360-20200228/specs/sealed-types-jls.html