RFR: 8320971: Use BufferedInputStream.buf directly when param of implTransferTo() is trusted [v19]

[Alan Bateman]

On Sat, 30 Dec 2023 16:47:11 GMT, Sergey Tsypanov <stsypanov at openjdk.org> wrote:

>> It looks like we can skip copying of `byte[]` in `BufferedInputStream.implTransferTo()` for `OutputStreams` residing in `java.io`.
>> 
>> See comment by @vlsi in https://github.com/openjdk/jdk/pull/10525/files#diff-e19c508d1bb6ee78697ecca66947c395adda0d9c49a85bf696e677ecbd977af1R612
>
> Sergey Tsypanov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8320971: Fix JavaDoc

Implementation changes looks fine, that's for taking all the feedback to get this one to a good place.

@bplb has been reviewing the test, I'll stay out of that and let Brian finish his review.

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Marked as reviewed by alanb (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/16879#pullrequestreview-1800627205