RFR: 8291660: Grapheme support in BreakIterator

Tue Aug 23 22:54:12 UTC 2022

This is to enhance the character break analysis in `java.text.BreakIterator` to conform to the extended grapheme cluster boundaries defined in https://www.unicode.org/reports/tr29/#Grapheme_Cluster_Boundaries. A corresponding CSR has also been drafted, as there will be behavioral changes with this modification.

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Commit messages:
 - 8291660: Grapheme support in BreakIterator
 - 8291660: Add a method to stream extended grapheme clusters in a String

Changes: https://git.openjdk.org/jdk/pull/9991/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9991&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8291660
  Stats: 251 lines in 10 files changed: 170 ins; 48 del; 33 mod
  Patch: https://git.openjdk.org/jdk/pull/9991.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9991/head:pull/9991

PR: https://git.openjdk.org/jdk/pull/9991