2.x: Workaround for Objects.requireNonNull inserted by javac

[akarnokd]

For some reason, when compiling RxJava with Java 9 or 10 and target 8, there is an implicit Objects.requireNonNull added by the compiler to us.new X which makes AnimalSniffer detect a non-Java 6 API usage. Interestingly, this does not happen with:

• Java 8 target 6,
• Java 8 target 8,
• Java 9 target 6,
• Java 9 target 9,
• Java 10 target 6,
• Java 10 target 9,
• Java 10 target 10

or AnimalSniffer doesn't detect it for non-8 targets somehow. I know that the latest AnimalSniffer doesn't work with (some?) Java 9 class files, but it doesn't explain why the fully supported Java 8 target 8 does not trigger this error but Java 9 target 8 does.

I have reported this anomaly as a potential javac bug.

The build matrices and outcomes for RxJava 2 can be found here: https://travis-ci.org/akarnokd/RxJava2_9/builds

[JakeWharton]

I remember this problem occurring because of Error Prone a while back.

[codecov]

Codecov Report

Merging #5966 into 2.x will increase coverage by 0.02%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##                2.x   #5966      +/-   ##
===========================================
+ Coverage     98.27%   98.3%   +0.02%     
  Complexity     6018    6018              
===========================================
  Files           656     656              
  Lines         44037   44037              
  Branches       6100    6100              
===========================================
+ Hits          43278   43289      +11     
+ Misses          225     220       -5     
+ Partials        534     528       -6

Impacted Files	Coverage Δ	Complexity Δ
...tivex/internal/observers/FutureSingleObserver.java	94.33% <0%> (-3.78%)	24% <0%> (-1%)
...ternal/operators/observable/ObservablePublish.java	96.46% <0%> (-3.54%)	11% <0%> (ø)
...nternal/operators/observable/ObservableWindow.java	98% <0%> (-2%)	3% <0%> (ø)
...rnal/operators/observable/ObservableSwitchMap.java	93.61% <0%> (-1.07%)	3% <0%> (ø)
...perators/observable/ObservableMergeWithSingle.java	99.06% <0%> (-0.94%)	2% <0%> (ø)
...rnal/operators/mixed/ObservableConcatMapMaybe.java	99.18% <0%> (-0.82%)	3% <0%> (ø)
...al/operators/observable/ObservableWindowTimed.java	90.73% <0%> (-0.82%)	4% <0%> (ø)
...nternal/operators/observable/ObservableReplay.java	98.08% <0%> (-0.55%)	23% <0%> (ø)
...x/internal/operators/flowable/FlowableFlatMap.java	89.47% <0%> (-0.53%)	4% <0%> (ø)
...ex/internal/operators/flowable/FlowableReplay.java	94.08% <0%> (-0.22%)	23% <0%> (ø)
... and 16 more

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[akarnokd]

I guess this was that issue: google/error-prone#375