<i18n dev> RFR: 6218123: (cal) API: Spec for GregorianCalendar constructors and Calendar getInstance is inconsistent.

Fri Apr 7 17:27:40 UTC 2023

The GregorianCalendar constructors and Calendar.getInstance() methods that take TimeZone or Locale throw a NullPointerException if any values are null. 

This PR updates the javadoc to make this apparent.

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Commit messages:
 - Adjust wording
 - Document exceptions

Changes: https://git.openjdk.org/jdk/pull/13310/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13310&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-6218123
  Stats: 7 lines in 2 files changed: 6 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/13310.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13310/head:pull/13310

PR: https://git.openjdk.org/jdk/pull/13310