YARN-10708. Remove NULL checks before instanceof

[TJJack]

JIRA ISSUE: https://issues.apache.org/jira/browse/YARN-10708

[hadoop-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	0m 37s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 1s		codespell was not available.
+1 💚	@author	0m 0s		The patch does not contain any @author tags.
-1 ❌	test4tests	0m 1s		The patch doesn't appear to include any new or modified tests. Please justify why no new tests are needed for this patch. Also please list what manual steps were performed to verify this patch.
			_ trunk Compile Tests _
+0 🆗	mvndep	14m 21s		Maven dependency ordering for branch
+1 💚	mvninstall	20m 44s		trunk passed
+1 💚	compile	9m 47s		trunk passed with JDK Ubuntu-11.0.10+9-Ubuntu-0ubuntu1.20.04
+1 💚	compile	7m 58s		trunk passed with JDK Private Build-1.8.0_282-8u282-b08-0ubuntu1~20.04-b08
+1 💚	checkstyle	1m 45s		trunk passed
+1 💚	mvnsite	3m 46s		trunk passed
+1 💚	javadoc	3m 15s		trunk passed with JDK Ubuntu-11.0.10+9-Ubuntu-0ubuntu1.20.04
+1 💚	javadoc	3m 28s		trunk passed with JDK Private Build-1.8.0_282-8u282-b08-0ubuntu1~20.04-b08
+1 💚	spotbugs	6m 59s		trunk passed
+1 💚	shadedclient	15m 4s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+0 🆗	mvndep	0m 25s		Maven dependency ordering for patch
+1 💚	mvninstall	2m 30s		the patch passed
+1 💚	compile	10m 38s		the patch passed with JDK Ubuntu-11.0.10+9-Ubuntu-0ubuntu1.20.04
+1 💚	javac	10m 38s		the patch passed
+1 💚	compile	8m 35s		the patch passed with JDK Private Build-1.8.0_282-8u282-b08-0ubuntu1~20.04-b08
+1 💚	javac	8m 35s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	1m 38s		the patch passed
+1 💚	mvnsite	3m 25s		the patch passed
+1 💚	javadoc	2m 55s		the patch passed with JDK Ubuntu-11.0.10+9-Ubuntu-0ubuntu1.20.04
+1 💚	javadoc	3m 5s		the patch passed with JDK Private Build-1.8.0_282-8u282-b08-0ubuntu1~20.04-b08
+1 💚	spotbugs	7m 27s		the patch passed
+1 💚	shadedclient	14m 46s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	unit	1m 8s		hadoop-yarn-api in the patch passed.
+1 💚	unit	4m 54s		hadoop-yarn-common in the patch passed.
+1 💚	unit	2m 57s		hadoop-yarn-server-common in the patch passed.
+1 💚	unit	22m 59s		hadoop-yarn-server-nodemanager in the patch passed.
+1 💚	asflicense	0m 52s		The patch does not generate ASF License warnings.
		178m 30s

Subsystem	Report/Notes
Docker	ClientAPI=1.41 ServerAPI=1.41 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-2803/1/artifact/out/Dockerfile
GITHUB PR	#2803
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell
uname	Linux 86001b19b1af 4.15.0-58-generic #64-Ubuntu SMP Tue Aug 6 11:12:41 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / 146bc4c
Default Java	Private Build-1.8.0_282-8u282-b08-0ubuntu1~20.04-b08
Multi-JDK versions	/usr/lib/jvm/java-11-openjdk-amd64:Ubuntu-11.0.10+9-Ubuntu-0ubuntu1.20.04 /usr/lib/jvm/java-8-openjdk-amd64:Private Build-1.8.0_282-8u282-b08-0ubuntu1~20.04-b08
Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-2803/1/testReport/
Max. process+thread count	668 (vs. ulimit of 5500)
modules	C: hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager U: hadoop-yarn-project/hadoop-yarn
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-2803/1/console
versions	git=2.25.1 maven=3.6.3 spotbugs=4.2.2
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[virajjasani]

+1 (non-binding)

[TJJack]

Thanks @virajjasani, please help to merge, the check failures should not be related to these code changes.

[virajjasani]

I thought this was merged with #2804. FYI @goiri

[TJJack]

@virajjasani Exactly, many thanks for your kind reply.

[github-actions]

We're closing this stale PR because it has been open for 100 days with no activity. This isn't a judgement on the merit of the PR in any way. It's just a way of keeping the PR queue manageable.
If you feel like this was a mistake, or you would like to continue working on it, please feel free to re-open it and ask for a committer to remove the stale tag and review again.
Thanks all for your contribution.