RFR: JDK-8322512 StringBuffer.repeat does not work correctly after toString() was called [v3]

[Jim Laskey]

> The new repeat methods were not clearing the toStringCache.

Jim Laskey has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Merge remote-tracking branch 'upstream/master' into 8322512
 - Clear sooner
 - Clear toStringCache when calling StringBuffer::repeat

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17172/files
  - new: https://git.openjdk.org/jdk/pull/17172/files/66eb7f71..33dd7973

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17172&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17172&range=01-02

  Stats: 3615 lines in 286 files changed: 2156 ins; 564 del; 895 mod
  Patch: https://git.openjdk.org/jdk/pull/17172.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17172/head:pull/17172

PR: https://git.openjdk.org/jdk/pull/17172