RFR: 8138614: (spec str) StringBuffer and StringBuilder methods improperly require "new" String to be returned [v2]

[Stuart Marks]

> A couple adjustments to the specs for four methods of StringBuilder and StringBuffer so that they no longer require new Strings to be created, just a String with the right contents. No implementation changes. Note that the actual specs (and implementations) are actually in AbstractStringBuilder, and they're inherited by StringBuilder and StringBuffer.

Stuart Marks has updated the pull request incrementally with one additional commit since the last revision:

  A tiny bit of wordsmithing.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/23599/files
  - new: https://git.openjdk.org/jdk/pull/23599/files/074bd261..0633c022

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23599&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23599&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/23599.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23599/head:pull/23599

PR: https://git.openjdk.org/jdk/pull/23599