CSR review review for JDK-8296182: Start of release updates for JDK 21

[Joseph D. Darcy]

Hello,

Looking ahead to the start of JDK 21, please review the CSR for
    JDK-8296182: Start of release updates for JDK 21
    https://bugs.openjdk.org/browse/JDK-8296182

which adds a new enum constant to ClassFileFormatVersion.

(The draft PR https://github.com/openjdk/jdk/pull/10924 will bundle 
together this and several related changes closer to the start of JDK 21.)

Thanks,

-Joe