RFR: 8318124: JFR: Rewrite instrumentation to use Class-File API [v2]

[Chen Liang]

On Mon, 16 Oct 2023 05:02:01 GMT, Erik Gahlin <egahlin at openjdk.org> wrote:

>> src/jdk.jfr/share/classes/jdk/jfr/internal/EventInstrumentation.java line 204:
>> 
>>> 202:         String typeDescriptor = classDesc.descriptorString();
>>> 203:         for (ClassElement ce : classModel.elements()) {
>>> 204:             if (ce instanceof RuntimeVisibleAnnotationsAttribute rvaa) {
>> 
>> You can use `classModel.findAttribute(Attributes.RUNTIME_VISIBLE_ANNOTATIONS)` instead of looping.
>
> I could not get it to work with findAttribute. No annotations were found.

The existing code will silently finish the loop no-op and return `null` if no RVAA is present. So if `findAttribute` returns `Optional.empty()`, you should just return `null` to match the old behavior.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16195#discussion_r1360143716