Add tests for AffineConverter.java

[Hardvan]

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized it.
• All filenames are in PascalCase.
• All functions and variable names follow Java naming conventions.
• All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• All new code is formatted with clang-format -i --style=file path/to/your/file.java

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 57.48%. Comparing base (25dc55e) to head (5265a99).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5602      +/-   ##
============================================
+ Coverage     57.46%   57.48%   +0.01%     
- Complexity     3640     3641       +1     
============================================
  Files           545      545              
  Lines         15708    15708              
  Branches       2994     2994              
============================================
+ Hits           9027     9030       +3     
+ Misses         6301     6300       -1     
+ Partials        380      378       -2     

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[siriak]

Looks good, thanks!

[Hardvan]

Thanks!