Clarifications and small fixes for checking JSpecify @Nullable annotation

[msridhar]

Rename a variable and add docs to clarify that in certain places, our JSpecify support specifically checks for @org.jspecify.annotations.Nullable annotations and not others. Also, fix a couple of places where we were comparing types by their String representation.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (60648a9) 86.95% compared to head (c2677a1) 87.02%.

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #859      +/-   ##
============================================
+ Coverage     86.95%   87.02%   +0.07%     
- Complexity     1919     1921       +2     
============================================
  Files            77       77              
  Lines          6215     6219       +4     
  Branches       1209     1209              
============================================
+ Hits           5404     5412       +8     
+ Misses          405      403       -2     
+ Partials        406      404       -2     

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[yuxincs]

Refactor and fixes LGTM 👍

Thanks for the clarifications!

(BTW do we want to allow 1% of coverage differences? codecov's coverage calculation is a bit imprecise)

[msridhar]

(BTW do we want to allow 1% of coverage differences? codecov's coverage calculation is a bit imprecise)

It turns out the coverage issue was real and I added a test to cover another case. So in this case it was useful 🙂 As the codecov jobs are non-blocking for NullAway I think we can (for now) leave them as failing even with a small change