RFR: 8306308: (ch) Writer created by Channels::newWriter may lose data [v8]

[Brian Burkhalter]

> Change `Channels.newWriter` to return a `Writer` created by first wrapping the `WritableByteChannel` in an `OutputStream` using `Channels.newOutputStream` and then wrapping the result in an `OutputStreamWriter`. With this change in place, the problems reported in the issue do not occur.

Brian Burkhalter has updated the pull request incrementally with one additional commit since the last revision:

  8306308: Really fix test

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Changes:
  - all: https://git.openjdk.org/jdk/pull/16207/files
  - new: https://git.openjdk.org/jdk/pull/16207/files/f1b74f08..850ffd6b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16207&range=07
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16207&range=06-07

  Stats: 16 lines in 1 file changed: 1 ins; 2 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/16207.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16207/head:pull/16207

PR: https://git.openjdk.org/jdk/pull/16207