<i18n dev> RFR: 8311528: Remove IDE specific SuppressWarnings

[Naoto Sato]

Removing the IDE specific `@SuppressWarnings` attached to `java.util.Calendar#equals()`. `equals()` implementation now checks the type of the other instance for this.

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Commit messages:
 - initial commit

Changes: https://git.openjdk.org/jdk/pull/14790/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14790&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311528
  Stats: 15 lines in 1 file changed: 1 ins; 1 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/14790.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14790/head:pull/14790

PR: https://git.openjdk.org/jdk/pull/14790