RFR: JDK-8227046: compiler implementation for sealed classes, JDK-8227047: Javadoc for sealed types and JDK-8227044: javax.lang.model for sealed classes

[Vicente Romero]

Hi,

Please review this patch for the compiler, javadoc and javax.lang.model 
support for the JEP 360 Sealed Classes (Preview). The changes are 
provided at [1], which implements the latest JLS for sealed types [2]. 
The patch also include the needed changes to javadoc and 
javax.lang.model to support sealed types. The CSR witht the changes in 
the javax.lang.model spec is at [3]. The sealed types JEP is accessible 
at [4]. There is an ongoing review for the VM and core-libs code of 
sealed types [5] and that code hasn't been included in this webrev,

Thanks,
Vicente

[1] http://cr.openjdk.java.net/~vromero/8227046/webrev.00/
[2] 
http://cr.openjdk.java.net/~gbierman/jep360/jep360-20200513/specs/sealed-classes-jls.html 

[3] https://bugs.openjdk.java.net/browse/JDK-8244367
[4] https://openjdk.java.net/jeps/360
[5] 
https://mail.openjdk.java.net/pipermail/core-libs-dev/2020-May/066440.html