RFR: JDK-8310835: Address gaps in -Xlint:serial checks [v3]

[Roger Riggs]

On Fri, 14 Jul 2023 23:37:38 GMT, Joe Darcy <darcy at openjdk.org> wrote:

>> Improve serial lint messages for externalizable records (and potentially other situations).
>
> Joe Darcy has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add support for externalizable enum checks.

test/langtools/tools/javac/warnings/Serial/EnumSerial.java line 5:

> 3:  * @bug 8202056
> 4:  * @compile/ref=EnumSerial.out -XDrawDiagnostics -Xlint:serial EnumSerial.java
> 5:  * @compile/ref=empty.out      -XDrawDiagnostics               EnumSerial.java

extra spaces snuck in

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PR Review Comment: https://git.openjdk.org/jdk/pull/14639#discussion_r1265635307