ISSUE-10781: Build failure because of spotbugs

[sijie]

Original Issue: apache#10781

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Describe the bug
Build failed with cmd mvn clean install -DskipTests when building Pulsar Functions :: Instance 2.8.0-SNAPSHOT [35/127]
Here is the main error logs:

[INFO] --- spotbugs-maven-plugin:4.2.2:check (check) @ pulsar-functions-instance ---
[INFO] BugInstance size is 1
[INFO] Error size is 0
[INFO] Total bugs: 1
[ERROR] Medium: Load of known null value in org.apache.pulsar.functions.instance.state.BKStateStoreImpl.lambda$getAsync$1(ByteBuf) [org.apache.pulsar.functions.instance.state.BKStateStoreImpl] At BKStateStoreImpl.java:[line 175] NP_LOAD_OF_KNOWN_NULL_VALUE
[INFO]

To see bug detail using the Spotbugs GUI, use the following command "mvn spotbugs:gui"

To Reproduce
Steps to reproduce the behavior:

1. clone repo from github.
2. mvn clean install -DskipTests
3. BUILD FAILURE

Expected behavior
build success

Desktop (please complete the following information):

pulsar git:(master) mvn -version
Apache Maven 3.8.1 (05c21c65bdfed0f71a2f2ada8b84da59348c4c5d)
Maven home: /Users/jason/apache-maven-3.8.1
Java version: 1.8.0_91, vendor: Oracle Corporation, runtime: /Library/Java/JavaVirtualMachines/jdk1.8.0_91.jdk/Contents/Home/jre
Default locale: zh_CN, platform encoding: UTF-8
OS name: "mac os x", version: "10.15.7", arch: "x86_64", family: "mac"

Additional context
I have tried these approaches:

1. update mvn version from 3.6.1 to the latest 3.8.1
2. clear mvn local cache in .m2/repository
3. change spotbugs plugin-version to 4.2.3 and 4.2.0
   Not working.

Although, It can be solved by add a null check in BKStateStoreImpl.java:[line 175] according to the error log.
But I can build in a clean linux server.
So it must have something to do with my labtop settings.

Any suggestions?