RFR: 8264208: Console charset API [v9]

[Naoto Sato]

> Please review the changes for the subject issue.  This has been suggested in a recent discussion thread for the JEP 400 [[1](https://mail.openjdk.java.net/pipermail/core-libs-dev/2021-March/075214.html)]. A CSR has also been drafted, and comments are welcome [[2](https://bugs.openjdk.java.net/browse/JDK-8264209)].

Naoto Sato has updated the pull request incrementally with one additional commit since the last revision:

  Modified javadocs per suggestions.

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3419/files
  - new: https://git.openjdk.java.net/jdk/pull/3419/files/5988f600..083f6180

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3419&range=08
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3419&range=07-08

  Stats: 3 lines in 2 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3419.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3419/head:pull/3419

PR: https://git.openjdk.java.net/jdk/pull/3419