<Swing Dev> RFR: 8231041: Spotbugs: Null check of value previously dereferenced in java.desktop

Tue Dec 22 19:45:05 UTC 2020

I checked JDK16 repository in SpotBugs 4.2.0
![изображение](https://user-images.githubusercontent.com/741251/102926543-405c9000-44a6-11eb-9772-bf81a22ec78a.png)
I fixed only places in java.desktop module.
I didn't fixed places, where dereferencing is done inside method.

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Commit messages:
 - 8231041: Spotbugs: Null check of value previously dereferenced in java.desktop

Changes: https://git.openjdk.java.net/jdk/pull/1869/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1869&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8231041
  Stats: 69 lines in 13 files changed: 13 ins; 36 del; 20 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1869.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1869/head:pull/1869

PR: https://git.openjdk.java.net/jdk/pull/1869