RFR: 8347946: Add API note that caller should validate/trust signers to the getCertificates and getCodeSigners methods of JarEntry and JarURLConnection

[Lance Andersen]

On Thu, 13 Feb 2025 16:27:03 GMT, Sean Mullan <mullan at openjdk.org> wrote:

> This change adds an API note to these methods recommending that the caller should perform further validation steps on the code signers that signed the JAR file, such as validating the code signer's certificate chain, and determining if the signer should be trusted. There was already a similar warning in the `JarFile` and `JarInputStream` class descriptions, but this adds a similar and more direct warning at the methods that return the code signer's certificates.
> 
> 2 other smaller changes:
>  - In `JarEntry.getCertificates`, added a recommendation to use the `getCodeSigners` method instead
>  - Added details of the order of the returned certificates to `JarURLConnection.getCertificates` (copied from `JarEntry.getCertificates`)

Marked as reviewed by lancea (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/23616#pullrequestreview-2618386370