HBASE-27068 NPE occurs when the active master has not yet been elected

[tomscut]

JIRA: HBASE-27068.

When the active master has not yet been elected. We access the master web UI, a NPE will be thrown out. Assertion is now added, but assertion in production is disabled by default. We can use Preconditions instead.

[Apache-HBase]

🎊 +1 overall

Vote	Subsystem	Runtime	Comment
+0 🆗	reexec	1m 0s	Docker mode activated.
		_ Prechecks _
+1 💚	dupname	0m 0s	No case conflicting files found.
+1 💚	@author	0m 0s	The patch does not contain any @author tags.
		_ master Compile Tests _
+1 💚	mvninstall	2m 22s	master passed
+1 💚	spotless	0m 43s	branch has no errors when running spotless:check.
		_ Patch Compile Tests _
+1 💚	mvninstall	2m 11s	the patch passed
+1 💚	whitespace	0m 0s	The patch has no whitespace issues.
+1 💚	spotless	0m 40s	patch has no errors when running spotless:check.
		_ Other Tests _
+1 💚	asflicense	0m 11s	The patch does not generate ASF License warnings.
		8m 20s

Subsystem	Report/Notes
Docker	ClientAPI=1.41 ServerAPI=1.41 base: https://ci-hbase.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-4474/1/artifact/yetus-general-check/output/Dockerfile
GITHUB PR	#4474
Optional Tests	dupname asflicense javac spotless
uname	Linux 3e912184c90c 5.4.0-90-generic #101-Ubuntu SMP Fri Oct 15 20:00:55 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/hbase-personality.sh
git revision	master / cf0ed2e
Default Java	AdoptOpenJDK-1.8.0_282-b08
Max. process+thread count	69 (vs. ulimit of 30000)
modules	C: hbase-server U: hbase-server
Console output	https://ci-hbase.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-4474/1/console
versions	git=2.17.1 maven=3.6.3
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[Apache-HBase]

💔 -1 overall

Vote	Subsystem	Runtime	Comment
+0 🆗	reexec	0m 41s	Docker mode activated.
-0 ⚠️	yetus	0m 2s	Unprocessed flag(s): --brief-report-file --spotbugs-strict-precheck --whitespace-eol-ignore-list --whitespace-tabs-ignore-list --quick-hadoopcheck
		_ Prechecks _
		_ master Compile Tests _
+1 💚	mvninstall	4m 9s	master passed
+1 💚	javadoc	0m 25s	master passed
		_ Patch Compile Tests _
+1 💚	mvninstall	2m 19s	the patch passed
+1 💚	javadoc	0m 22s	the patch passed
		_ Other Tests _
-1 ❌	unit	187m 56s	hbase-server in the patch failed.
		197m 12s

Subsystem	Report/Notes
Docker	ClientAPI=1.41 ServerAPI=1.41 base: https://ci-hbase.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-4474/1/artifact/yetus-jdk11-hadoop3-check/output/Dockerfile
GITHUB PR	#4474
Optional Tests	javac javadoc unit
uname	Linux e0b908777345 5.4.0-1071-aws #76~18.04.1-Ubuntu SMP Mon Mar 28 17:49:57 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/hbase-personality.sh
git revision	master / cf0ed2e
Default Java	AdoptOpenJDK-11.0.10+9
unit	https://ci-hbase.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-4474/1/artifact/yetus-jdk11-hadoop3-check/output/patch-unit-hbase-server.txt
Test Results	https://ci-hbase.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-4474/1/testReport/
Max. process+thread count	2557 (vs. ulimit of 30000)
modules	C: hbase-server U: hbase-server
Console output	https://ci-hbase.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-4474/1/console
versions	git=2.17.1 maven=3.6.3
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[Apache-HBase]

🎊 +1 overall

Vote	Subsystem	Runtime	Comment
+0 🆗	reexec	0m 39s	Docker mode activated.
-0 ⚠️	yetus	0m 3s	Unprocessed flag(s): --brief-report-file --spotbugs-strict-precheck --whitespace-eol-ignore-list --whitespace-tabs-ignore-list --quick-hadoopcheck
		_ Prechecks _
		_ master Compile Tests _
+1 💚	mvninstall	3m 59s	master passed
+1 💚	javadoc	0m 23s	master passed
		_ Patch Compile Tests _
+1 💚	mvninstall	2m 3s	the patch passed
+1 💚	javadoc	0m 21s	the patch passed
		_ Other Tests _
+1 💚	unit	194m 11s	hbase-server in the patch passed.
		202m 56s

Subsystem	Report/Notes
Docker	ClientAPI=1.41 ServerAPI=1.41 base: https://ci-hbase.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-4474/1/artifact/yetus-jdk8-hadoop3-check/output/Dockerfile
GITHUB PR	#4474
Optional Tests	javac javadoc unit
uname	Linux 93111eb01007 5.4.0-1071-aws #76~18.04.1-Ubuntu SMP Mon Mar 28 17:49:57 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/hbase-personality.sh
git revision	master / cf0ed2e
Default Java	AdoptOpenJDK-1.8.0_282-b08
Test Results	https://ci-hbase.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-4474/1/testReport/
Max. process+thread count	2624 (vs. ulimit of 30000)
modules	C: hbase-server U: hbase-server
Console output	https://ci-hbase.apache.org/job/HBase-PreCommit-GitHub-PR/job/PR-4474/1/console
versions	git=2.17.1 maven=3.6.3
Powered by	Apache Yetus 0.12.0 https://yetus.apache.org

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[tomscut]

Hi @virajjasani @pankaj72981 , could you please take a look. Thanks.

[tomscut]

Thanks @virajjasani for the review.

[tomscut]

Thanks @pankaj72981 for the review.