RFR: 8334772: Change Class::protectionDomain and signers to explicit fields

[Chen Liang]

On Wed, 17 Jul 2024 17:47:11 GMT, Chen Liang <liach at openjdk.org> wrote:

> Please review this change that moves `Class.protectionDomain` and `signers` to explicit fields.
> 
> Related native methods in `Class` and `AccessController::getProtectionDomain` are converted to pure Java. These fields are still set and used by hotspot. Also fixes the incorrect `protectiondomain_signature` in `vmSymbols`, which is actually an array descriptor.
> 
> Note that these new fields are not filtered: filtering in early bootstrap requires other unrelated adjustments as we can't even use hashCode on String, and filtering is not proper encapsulation either.

The migration of signers will be in a new PR. This patch will be kept so people will know the extra test updates related to migration of protectionDomain.

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PR Comment: https://git.openjdk.org/jdk/pull/20221#issuecomment-2234008622