Add a unit test for AddedVersusDeletedLinesCommitStatisticsSeriesBuilder

[Tjuri]

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[uhafner]

Seems that Jenkins does not mark the build as failed.

[uhafner]

See https://ci.jenkins.io/job/Plugins/job/forensics-api-plugin/job/PR-346/2/pmd/

[codecov]

Codecov Report

Merging #346 (7806e09) into master (237fba3) will increase coverage by 0.54%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master     #346      +/-   ##
============================================
+ Coverage     50.04%   50.59%   +0.54%     
- Complexity      253      256       +3     
============================================
  Files            42       42              
  Lines          1093     1093              
  Branches         92       92              
============================================
+ Hits            547      553       +6     
+ Misses          510      504       -6     
  Partials         36       36              

Impacted Files	Coverage Δ
.../jenkins/plugins/forensics/miner/SizePieChart.java	0.00% <0.00%> (ø)
...AddedVersusDeletedLinesForensicsSeriesBuilder.java	66.66% <0.00%> (+66.66%)	⬆️
...rsusDeletedLinesCommitStatisticsSeriesBuilder.java	100.00% <0.00%> (+100.00%)	⬆️

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