<i18n dev> RFR: 8369452: Locale.Builder.setLanguageTag(String) does not clear on empty or null String [v2]

[Justin Lu]

> Please review this PR which corrects the behavior of `Locale.Builder.setLanguageTag(String)` on the null and empty String case.
> 
> This method is specified as follows,
> 
>> Null and the empty string cause the builder to be reset
> 
> Currently, NPE is thrown for a null tag, and ILE is thrown for an empty String. They are both corrected to not throw, and instead reset the state of the `Locale.Builder`.

Justin Lu has updated the pull request incrementally with one additional commit since the last revision:

  Naoto's comment - improve err msg

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Changes:
  - all: https://git.openjdk.org/jdk/pull/27734/files
  - new: https://git.openjdk.org/jdk/pull/27734/files/68bb29a1..fa385c8a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27734&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27734&range=00-01

  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/27734.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27734/head:pull/27734

PR: https://git.openjdk.org/jdk/pull/27734