HADOOP-18690: Fix for Javac Error of Unchecked Cast

[anujmodi2021]

Description of PR

This PR fixes the Unchecked Cast Error/Warning thrown at javac step of yetus checks on PR.
Jira ticket: https://issues.apache.org/jira/browse/HADOOP-18690

Fix is to deterministically type cast the return type of the function.
Since there is only one return type possible for the function, there is no need to type cast it.

[anujmodi2021]

The only possible return type from this function (apart from null) is "Token<DelegationTokenIdentifier>". Therefore it seems safe to deterministically define the return type instead of generic return type here. This will solve the Unchecked Cast Error.

[hadoop-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	0m 42s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 0s		codespell 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.
			_ branch-3.3.4 Compile Tests _
+1 💚	mvninstall	37m 52s		branch-3.3.4 passed
+1 💚	compile	0m 37s		branch-3.3.4 passed
+1 💚	checkstyle	0m 30s		branch-3.3.4 passed
+1 💚	mvnsite	0m 40s		branch-3.3.4 passed
+1 💚	javadoc	0m 35s		branch-3.3.4 passed
+1 💚	spotbugs	1m 17s		branch-3.3.4 passed
+1 💚	shadedclient	24m 49s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	0m 33s		the patch passed
+1 💚	compile	0m 28s		the patch passed
-1 ❌	javac	0m 28s	/results-compile-javac-hadoop-tools_hadoop-azure.txt	hadoop-tools_hadoop-azure generated 1 new + 18 unchanged - 1 fixed = 19 total (was 19)
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	0m 18s		the patch passed
+1 💚	mvnsite	0m 30s		the patch passed
+1 💚	javadoc	0m 22s		the patch passed
+1 💚	spotbugs	1m 8s		the patch passed
+1 💚	shadedclient	23m 47s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	unit	1m 56s		hadoop-azure in the patch passed.
+1 💚	asflicense	0m 38s		The patch does not generate ASF License warnings.
		98m 17s

Subsystem	Report/Notes
Docker	ClientAPI=1.42 ServerAPI=1.42 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-5535/1/artifact/out/Dockerfile
GITHUB PR	#5535
JIRA Issue	HADOOP-18690
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell
uname	Linux b642ee76a61f 4.15.0-206-generic #217-Ubuntu SMP Fri Feb 3 19:10:13 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	branch-3.3.4 / 1ddc911
Default Java	Private Build-1.8.0_362-8u362-ga-0ubuntu1~18.04.1-b09
Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-5535/1/testReport/
Max. process+thread count	540 (vs. ulimit of 5500)
modules	C: hadoop-tools/hadoop-azure U: hadoop-tools/hadoop-azure
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-5535/1/console
versions	git=2.17.1 maven=3.6.0 spotbugs=4.2.2
Powered by	Apache Yetus 0.14.0-SNAPSHOT https://yetus.apache.org

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[hadoop-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	1m 0s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 1s		No case conflicting files found.
+0 🆗	codespell	0m 0s		codespell was not available.
+1 💚	@author	0m 0s		The patch does not contain any @author tags.
+1 💚	test4tests	0m 0s		The patch appears to include 1 new or modified test files.
			_ branch-3.3.4 Compile Tests _
+1 💚	mvninstall	39m 17s		branch-3.3.4 passed
+1 💚	compile	0m 32s		branch-3.3.4 passed
+1 💚	checkstyle	0m 27s		branch-3.3.4 passed
+1 💚	mvnsite	0m 38s		branch-3.3.4 passed
+1 💚	javadoc	0m 29s		branch-3.3.4 passed
+1 💚	spotbugs	1m 18s		branch-3.3.4 passed
+1 💚	shadedclient	27m 22s		branch has no errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	0m 32s		the patch passed
+1 💚	compile	0m 30s		the patch passed
-1 ❌	javac	0m 30s	/results-compile-javac-hadoop-tools_hadoop-azure.txt	hadoop-tools_hadoop-azure generated 2 new + 17 unchanged - 2 fixed = 19 total (was 19)
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	0m 17s		the patch passed
+1 💚	mvnsite	0m 33s		the patch passed
+1 💚	javadoc	0m 20s		the patch passed
+1 💚	spotbugs	1m 17s		the patch passed
+1 💚	shadedclient	26m 44s		patch has no errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	unit	2m 6s		hadoop-azure in the patch passed.
+1 💚	asflicense	0m 32s		The patch does not generate ASF License warnings.
		104m 34s

Subsystem	Report/Notes
Docker	ClientAPI=1.42 ServerAPI=1.42 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-5535/2/artifact/out/Dockerfile
GITHUB PR	#5535
JIRA Issue	HADOOP-18690
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell
uname	Linux ead33f932db0 4.15.0-206-generic #217-Ubuntu SMP Fri Feb 3 19:10:13 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	branch-3.3.4 / 2744731
Default Java	Private Build-1.8.0_362-8u362-ga-0ubuntu1~18.04.1-b09
Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-5535/2/testReport/
Max. process+thread count	518 (vs. ulimit of 5500)
modules	C: hadoop-tools/hadoop-azure U: hadoop-tools/hadoop-azure
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-5535/2/console
versions	git=2.17.1 maven=3.6.0 spotbugs=4.2.2
Powered by	Apache Yetus 0.14.0-SNAPSHOT https://yetus.apache.org

This message was automatically generated.

[ayushtkn]

3.3..4 branch is released. No changes accepted for this branch. Closing