RFR: JDK-8302323 Add repeat methods to StringBuilder/StringBuffer [v10]

[Claes Redestad]

On Mon, 27 Mar 2023 18:37:12 GMT, Jim Laskey <jlaskey at openjdk.org> wrote:

>> Add the ability to repeatedly append char and CharSequence data to StringBuilder/StringBuffer.
>
> Jim Laskey has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Use Arrays.fill

Looks ok. I don't have a strong opinion on insert-repeat. 

I think tests that check for illegal code points should use a legal repeat value.

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Marked as reviewed by redestad (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/12728#pullrequestreview-1360764390