HDFS-16629. [JDK 11] Fix javadoc warnings in hadoop-hdfs module.

[slfan1989]

JIRA: HDFS-16629. [JDK 11] Fix javadoc warnings in hadoop-hdfs module.

During compilation of the most recently committed code, a java doc waring appeared and I will fix it.

the error in the compilation report(PR-4419、PR-4406)

1 error
100 warnings
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  37.132 s
[INFO] Finished at: 2022-06-09T17:07:12Z
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-javadoc-plugin:3.0.1:javadoc-no-fork (default-cli) on project hadoop-hdfs: An error has occurred in Javadoc report generation: 
[ERROR] Exit code: 1 - javadoc: warning - You have specified the HTML version as HTML 4.01 by using the -html4 option.
[ERROR] The default is currently HTML5 and the support for HTML 4.01 will be removed
[ERROR] in a future release. To suppress this warning, please ensure that any HTML constructs 

this repair will take a long time.

[hadoop-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	0m 36s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 1s		codespell was not available.
+0 🆗	detsecrets	0m 1s		detect-secrets was not available.
+1 💚	@author	0m 0s		The patch does not contain any @author tags.
-1 ❌	test4tests	0m 0s		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 _
+1 💚	mvninstall	37m 32s		trunk passed
+1 💚	compile	1m 44s		trunk passed with JDK Private Build-11.0.15+10-Ubuntu-0ubuntu0.20.04.1
+1 💚	compile	1m 34s		trunk passed with JDK Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
+1 💚	checkstyle	1m 24s		trunk passed
+1 💚	mvnsite	1m 50s		trunk passed
-1 ❌	javadoc	1m 22s	/branch-javadoc-hadoop-hdfs-project_hadoop-hdfs-jdkPrivateBuild-11.0.15+10-Ubuntu-0ubuntu0.20.04.1.txt	hadoop-hdfs in trunk failed with JDK Private Build-11.0.15+10-Ubuntu-0ubuntu0.20.04.1.
+1 💚	javadoc	1m 46s		trunk passed with JDK Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
+1 💚	spotbugs	3m 53s		trunk passed
+1 💚	shadedclient	23m 33s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	1m 24s		the patch passed
+1 💚	compile	1m 33s		the patch passed with JDK Private Build-11.0.15+10-Ubuntu-0ubuntu0.20.04.1
+1 💚	javac	1m 33s		the patch passed
+1 💚	compile	1m 49s		the patch passed with JDK Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
+1 💚	javac	1m 49s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	0m 59s		the patch passed
+1 💚	mvnsite	1m 28s		the patch passed
+1 💚	javadoc	0m 54s		hadoop-hdfs-project_hadoop-hdfs-jdkPrivateBuild-11.0.15+10-Ubuntu-0ubuntu0.20.04.1 with JDK Private Build-11.0.15+10-Ubuntu-0ubuntu0.20.04.1 generated 0 new + 99 unchanged - 1 fixed = 99 total (was 100)
+1 💚	javadoc	1m 26s		the patch passed with JDK Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
+1 💚	spotbugs	3m 29s		the patch passed
+1 💚	shadedclient	24m 20s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
-1 ❌	unit	256m 14s	/patch-unit-hadoop-hdfs-project_hadoop-hdfs.txt	hadoop-hdfs in the patch passed.
+1 💚	asflicense	1m 5s		The patch does not generate ASF License warnings.
		367m 34s

Reason	Tests
Failed junit tests	hadoop.hdfs.server.datanode.fsdataset.impl.TestLazyPersistReplicaPlacement
	hadoop.hdfs.TestRollingUpgrade

Subsystem	Report/Notes
Docker	ClientAPI=1.41 ServerAPI=1.41 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-4423/1/artifact/out/Dockerfile
GITHUB PR	#4423
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell detsecrets
uname	Linux 1f9aad630c2f 4.15.0-175-generic #184-Ubuntu SMP Thu Mar 24 17:48:36 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / 83c1f95
Default Java	Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
Multi-JDK versions	/usr/lib/jvm/java-11-openjdk-amd64:Private Build-11.0.15+10-Ubuntu-0ubuntu0.20.04.1 /usr/lib/jvm/java-8-openjdk-amd64:Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-4423/1/testReport/
Max. process+thread count	3368 (vs. ulimit of 5500)
modules	C: hadoop-hdfs-project/hadoop-hdfs U: hadoop-hdfs-project/hadoop-hdfs
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-4423/1/console
versions	git=2.25.1 maven=3.6.3 spotbugs=4.2.2
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