RFR: 8341566: Add Reader.of(CharSequence) [v7]

[Markus KARG]

On Thu, 10 Oct 2024 05:47:26 GMT, Markus KARG <duke at openjdk.org> wrote:

>> Currently uncontested locks have a performance regression after the removal of biased locking: A similar example with `StringBuffer` is available in #19513.
>
> I do not have any personal preferences here. The text was paraphrased from `StringBuilder`, so it seems it was acceptable in the past. If a different text is wanted, I would kindly ask all participants in this discussion to agree upon one common proposal, as I personally am fine with the text as-is.

Done; replaced by Alan's proposal: "Reader.of(CharSequence) provides a method to read from any CharSequence that may be more efficient than StringReader"

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PR Review Comment: https://git.openjdk.org/jdk/pull/21371#discussion_r1795762880