RFR: 8272137: Make Collection and Optional classes streamable

[Kevin Rushforth]

On Sun, 15 Aug 2021 02:45:17 GMT, CC007 <github.com+5381337+CC007 at openjdk.org> wrote:

>> create Streamable and ParallelStreamable interface and use them in Collection and Optional
>
> I read through [these posts](http://mail.openjdk.java.net/pipermail/lambda-libs-spec-experts/2013-June/thread.html#1910) and while I did see good reasons for not moving stream to Iterable, I didn't see any mention of a separate Streamable-like interface, so could you elaborate on that it "did not carry its weight"?

@CC007 Please follow the course of action that @briangoetz has requested. This needs to be discussed on the appropriate mailing list (core-libs-dev in this case) prior to submitting a pull request. It is premature to review this PR.

I invite you to refer to the [OpenJDK Developers' Guide](https://openjdk.java.net/guide/), specifically the [Socialize your change](https://openjdk.java.net/guide/#socialize-your-change) section.

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PR: https://git.openjdk.java.net/jdk/pull/5050