do code clean up

[arthur-zhang]

Description

Do some code clean up

Motivation and Context

some code do not match name convention or code style

Checklist:

• [x] My code follows the code style of this project.
• [x] I have updated the documentation accordingly.

[codecov-commenter]

Codecov Report

Merging #724 (abb0abc) into master (b73f690) will increase coverage by 0.00%. The diff coverage is 61.90%.

@@            Coverage Diff            @@
##             master     #724   +/-   ##
=========================================
  Coverage     55.24%   55.24%           
- Complexity    10386    10387    +1     
=========================================
  Files          1062     1062           
  Lines         65777    65777           
  Branches       7536     7536           
=========================================
+ Hits          36337    36339    +2     
+ Misses        26839    26838    -1     
+ Partials       2601     2600    -1     

Impacted Files	Coverage Δ
...pache/jmeter/report/dashboard/ReportGenerator.java	67.95% <ø> (ø)
...in/java/org/apache/jmeter/services/FileServer.java	71.71% <57.14%> (ø)
...va/org/apache/jmeter/engine/DistributedRunner.java	86.56% <60.00%> (ø)
...rg/apache/jmeter/control/ThroughputController.java	74.25% <100.00%> (ø)
...a/org/apache/jmeter/timers/PoissonRandomTimer.java	78.37% <0.00%> (+5.40%)	:arrow_up:

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