RFR: 8334772: Change Class::signers to an explicit field [v2]

[Alan Bateman]

On Thu, 18 Jul 2024 13:31:02 GMT, Chen Liang <liach at openjdk.org> wrote:

>> `Class` has 2 VM-injected fields that can be made explicit: `Object[] signers` and `ProtectionDomain protectionDomain`. We make the signers field explicit. (The ProtectionDomain can be revisited when SecurityManager is removed, as SecurityManager is accessing it via JNI as well.)
>> 
>> Migrate the JNI code to Java. The getter previously had a redundant primitive type check, which is dropped in the migrated Java code. The `Object[] getSigners` is no longer `native`, thus requiring a CSR record. Reviewers please help review the associated CSR.
>
> Chen Liang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Reorder comment of classData to avoid misunderstanding

Marked as reviewed by alanb (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/20223#pullrequestreview-2185842171