RFR: 8284637: Improve String.join performance [v2]

[XenoAmess]

On Mon, 11 Apr 2022 21:35:39 GMT, XenoAmess <duke at openjdk.java.net> wrote:

>> 8284637: Improve String.join performance
>
> XenoAmess has updated the pull request incrementally with one additional commit since the last revision:
> 
>   add jmh

JMH results shows not worthy. closed.

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PR: https://git.openjdk.java.net/jdk/pull/8169