RFR: 8290300: Use standard String-joining tools where applicable [v5]

[Сергей Цыпанов]

On Mon, 18 Jul 2022 18:40:51 GMT, Сергей Цыпанов <duke at openjdk.org> wrote:

>> Simplify code with `String.join()`
>
> Сергей Цыпанов has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8290300: Revert erroneous changes

Thanks!

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PR: https://git.openjdk.org/jdk/pull/9513