HADOOP-16556. Fix some alerts raised by LGTM

[malcolmtaylor]

Fix the following alerts:

• Array index out of bounds in KerberosName.java

• Contradictory type checks in GenericExceptionHandler

• Missing format argument in RegistrySecurity and HttpFSExceptionProvider

These alerts are shown in https://lgtm.com/projects/g/apache/hadoop/?mode=tree

[hadoop-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Comment
0	reexec	40	Docker mode activated.
		_ Prechecks _
+1	dupname	0	No case conflicting files found.
+1	@author	0	The patch does not contain any @author tags.
-1	test4tests	0	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	37	Maven dependency ordering for branch
+1	mvninstall	1232	trunk passed
+1	compile	1120	trunk passed
+1	checkstyle	164	trunk passed
-1	mvnsite	41	hadoop-yarn-common in trunk failed.
+1	shadedclient	1148	branch has no errors when building and testing our client artifacts.
+1	javadoc	142	trunk passed
0	spotbugs	48	Used deprecated FindBugs config; considering switching to SpotBugs.
-1	findbugs	40	hadoop-yarn-common in trunk failed.
		_ Patch Compile Tests _
0	mvndep	25	Maven dependency ordering for patch
-1	mvninstall	28	hadoop-yarn-common in the patch failed.
+1	compile	1087	the patch passed
+1	javac	1087	the patch passed
-0	checkstyle	150	root: The patch generated 1 new + 123 unchanged - 1 fixed = 124 total (was 124)
-1	mvnsite	39	hadoop-yarn-common in the patch failed.
+1	whitespace	0	The patch has no whitespace issues.
+1	shadedclient	772	patch has no errors when building and testing our client artifacts.
+1	javadoc	145	the patch passed
-1	findbugs	40	hadoop-yarn-common in the patch failed.
		_ Other Tests _
+1	unit	197	hadoop-auth in the patch passed.
+1	unit	64	hadoop-registry in the patch passed.
-1	unit	137	hadoop-hdfs-httpfs in the patch failed.
-1	unit	42	hadoop-yarn-common in the patch failed.
+1	asflicense	47	The patch does not generate ASF License warnings.
		7342

Reason	Tests
Failed junit tests	hadoop.fs.http.client.TestHttpFSWithHttpFSFileSystem
	hadoop.fs.http.client.TestHttpFSFWithSWebhdfsFileSystem
	hadoop.fs.http.client.TestHttpFSFWithWebhdfsFileSystem
	hadoop.fs.http.server.TestHttpFSServerNoXAttrs
	hadoop.fs.http.server.TestHttpFSServer
	hadoop.fs.http.client.TestHttpFSFileSystemLocalFileSystem
	hadoop.lib.service.hadoop.TestFileSystemAccessService
	hadoop.test.TestHFSTestCase
	hadoop.fs.http.server.TestHttpFSServerNoACLs

Subsystem	Report/Notes
Docker	Client=19.03.1 Server=19.03.1 base: https://builds.apache.org/job/hadoop-multibranch/job/PR-1428/1/artifact/out/Dockerfile
GITHUB PR	#1428
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient findbugs checkstyle
uname	Linux 2aea207d8df1 4.15.0-60-generic #67-Ubuntu SMP Thu Aug 22 16:55:30 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	personality/hadoop.sh
git revision	trunk / 44850f6
Default Java	1.8.0_222
mvnsite	https://builds.apache.org/job/hadoop-multibranch/job/PR-1428/1/artifact/out/branch-mvnsite-hadoop-yarn-project_hadoop-yarn_hadoop-yarn-common.txt
findbugs	https://builds.apache.org/job/hadoop-multibranch/job/PR-1428/1/artifact/out/branch-findbugs-hadoop-yarn-project_hadoop-yarn_hadoop-yarn-common.txt
mvninstall	https://builds.apache.org/job/hadoop-multibranch/job/PR-1428/1/artifact/out/patch-mvninstall-hadoop-yarn-project_hadoop-yarn_hadoop-yarn-common.txt
checkstyle	https://builds.apache.org/job/hadoop-multibranch/job/PR-1428/1/artifact/out/diff-checkstyle-root.txt
mvnsite	https://builds.apache.org/job/hadoop-multibranch/job/PR-1428/1/artifact/out/patch-mvnsite-hadoop-yarn-project_hadoop-yarn_hadoop-yarn-common.txt
findbugs	https://builds.apache.org/job/hadoop-multibranch/job/PR-1428/1/artifact/out/patch-findbugs-hadoop-yarn-project_hadoop-yarn_hadoop-yarn-common.txt
unit	https://builds.apache.org/job/hadoop-multibranch/job/PR-1428/1/artifact/out/patch-unit-hadoop-hdfs-project_hadoop-hdfs-httpfs.txt
unit	https://builds.apache.org/job/hadoop-multibranch/job/PR-1428/1/artifact/out/patch-unit-hadoop-yarn-project_hadoop-yarn_hadoop-yarn-common.txt
Test Results	https://builds.apache.org/job/hadoop-multibranch/job/PR-1428/1/testReport/
Max. process+thread count	306 (vs. ulimit of 5500)
modules	C: hadoop-common-project/hadoop-auth hadoop-common-project/hadoop-registry hadoop-hdfs-project/hadoop-hdfs-httpfs hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common U: .
Console output	https://builds.apache.org/job/hadoop-multibranch/job/PR-1428/1/console
versions	git=2.7.4 maven=3.3.9 findbugs=3.1.0-RC1
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[steveloughran]

nice catch

[steveloughran]

+1, merged into trunk. Thanks!