RFR: 8296734: JarVerifier:: mapSignersToCodeSource should cache in map [v4]

[Weijun Wang]

On Sat, 19 Nov 2022 04:31:13 GMT, pandaapo <duke at openjdk.org> wrote:

>> The cache named `signerToCodeSource` in `JarVerifier` is never used now.
>
> pandaapo has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Modify as reviews.

BTW, since this bug description is about a coding error but you fix is about cleanup, how about I file another bug and you use it in the title? I am trying to add a `noreg-cleanup` label to the bug and it does not apply to the jdk8u fix (suppose there will be one).

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PR: https://git.openjdk.org/jdk/pull/11072