RFR: 8295302: Do not use ArrayList when LambdaForm has a single ClassData [v2]

[Ioi Lam]

On Fri, 14 Oct 2022 17:12:51 GMT, Mandy Chung <mchung at openjdk.org> wrote:

>> src/java.base/share/classes/java/lang/invoke/InvokerBytecodeGenerator.java line 291:
>> 
>>> 289:         final List<ClassData> cd = classData;
>>> 290:         return switch(cd.size()) {
>>> 291:             case 0 -> null;
>> 
>> `List.of()` always returns the same singleton instance and does not cause any object allocation.  I prefer to keep the `classDataValues()` to return `List<Object>`
>
> Ah, I now see why you have to change the signature because of the single element case.  I made my comment too quickly. 
> 
> A couple of suggestions:
> Please add a javadoc for this method to describe what this method returns for different cases.   It's better to move this method close to `clinit` as they are tightly coupled.

I moved the method and added in javadoc. Could you check if the wording is OK?

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PR: https://git.openjdk.org/jdk/pull/10706