<i18n dev> RFR: 8293008: Replace uses of StringBuffer with StringBuilder in MergeCollation [v2]

[Andrey Turbanov]

> Couple of package-private classes in `java.text` package still use `StringBuffer`: `MergeCollation` and `PatternEntry`.
> StringBuffer is a legacy synchronized class. StringBuilder is a direct replacement to StringBuffer which generally have better performance.

Andrey Turbanov has updated the pull request incrementally with one additional commit since the last revision:

  8293008: Replace uses of StringBuffer with StringBuilder in MergeCollation
  
  use private for methods which changed signature

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Changes:
  - all: https://git.openjdk.org/jdk/pull/10007/files
  - new: https://git.openjdk.org/jdk/pull/10007/files/a53bcac0..e85e3c34

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10007&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10007&range=00-01

  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/10007.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10007/head:pull/10007

PR: https://git.openjdk.org/jdk/pull/10007