[ISSUE #2904]Fix unit test stability

[ayanamist]

Make sure set the target branch to develop

What is the purpose of the change

Improve unit test stability. mvn clean package sometimes will fail with strange issues, and retry will solve it. So i try to fix and stabilize these issues.

Brief changelog

I found the main issue is caused by powermock & mockito compatibility which results strange mock problems, so i remove powermock dependency.

Verifying this change

fix 2904

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• Run mvn -B clean apache-rat:check findbugs:findbugs checkstyle:checkstyle to make sure basic checks pass. Run mvn clean install -DskipITs to make sure unit-test pass. Run mvn clean test-compile failsafe:integration-test to make sure integration-test pass.
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[coveralls]

Coverage increased (+1.7%) to 54.079% when pulling 1350c3f on ayanamist:fix-test into be6eaf8 on apache:develop.