<i18n dev> RFR: 8274640: Cleanup unnecessary null comparison before instanceof check in java.desktop [v2]

[Andrey Turbanov]

> Updated code checks both non-null and instance of a class in java.desktop module classes.
> The checks and explicit casts could also be replaced with pattern matching for the instanceof operator. 
> Similar cleanups
> 1. [JDK-8273484](https://bugs.openjdk.java.net/browse/JDK-8273484) java.naming
> 2. [JDK-8258422](https://bugs.openjdk.java.net/browse/JDK-8258422) java.base

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

  8274640: Cleanup unnecessary null comparison before instanceof check in java.desktop
  apply review comments

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5482/files
  - new: https://git.openjdk.java.net/jdk/pull/5482/files/250ba2c4..5a8cf2fb

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5482&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5482&range=00-01

  Stats: 32 lines in 8 files changed: 0 ins; 1 del; 31 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5482.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5482/head:pull/5482

PR: https://git.openjdk.java.net/jdk/pull/5482