RFR: 8353795: Add Writer.of(StringBuilder) [v2]

[Markus KARG]

On Sun, 4 May 2025 16:21:41 GMT, Markus KARG <duke at openjdk.org> wrote:

>> This Pull Requests proposes an implementation for [JDK-8353795](https://bugs.openjdk.org/browse/JDK-8353795): Adding the new method `public static Writer Writer.of(StringBuilder)`, providing a non-synchronized Writer implementation optimized for writing into `StringBuilder`.
>> 
>> A basic test is provided to proof that the new `Writer` behaves as expected. For comparison, the same test is also run against `StringWriter`.
>
> Markus KARG has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Undone copyright update of otherwise unchanged file.
>  - Update Of.java
>    
>    Applied changnes proposed by @liach: "the default toString already includes id=..., so I usually don't provide an explicit override to make the code concise."

> There is some wording around this topic in the guide already: _In order to prepare the community for your patch, please socialize your idea on the relevant [mailing lists](https://openjdk.org/guide/#mailing-lists). Almost all changes, and in particular any API changes, must go this route and have a broad agreement in place before there is any point in presenting code._
> 
> I've added the suggested text to clarify this paragraph: [openjdk/guide#150](https://github.com/openjdk/guide/pull/150)

Then I can literally stop working on OpenJDK rather immediately, as people never find enough time for **"broad"** agreement. At least they didn't in the past **years**.

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PR Comment: https://git.openjdk.org/jdk/pull/24469#issuecomment-2855892549