use bounded wildcards for errorHandler (fixes #5045)

[jschneider]

Adding bound wildcards for error handler - fixes #5045

[codecov]

Codecov Report

Merging #5049 into 2.x will increase coverage by 0.12%.

@@             Coverage Diff              @@
##                2.x    #5049      +/-   ##
============================================
+ Coverage     95.53%   95.65%   +0.12%     
- Complexity     5540     5547       +7     
============================================
  Files           612      612              
  Lines         39576    39576              
  Branches       5553     5553              
============================================
+ Hits          37807    37855      +48     
+ Misses          775      742      -33     
+ Partials        994      979      -15

Impacted Files	Coverage Δ	Complexity Δ
.../main/java/io/reactivex/plugins/RxJavaPlugins.java	100% <100%> (ø)	138 <3> (ø)	❌
...vex/internal/operators/single/SingleTakeUntil.java	86.88% <ø> (-4.92%)	2% <ø> (ø)
...ternal/operators/flowable/FlowableSubscribeOn.java	94.54% <ø> (-3.64%)	2% <ø> (ø)
...reactivex/internal/operators/maybe/MaybeUsing.java	97.97% <ø> (-2.03%)	4% <ø> (ø)
...internal/operators/completable/CompletableAmb.java	94.44% <ø> (-1.86%)	10% <ø> (ø)
.../io/reactivex/disposables/CompositeDisposable.java	97.24% <ø> (-1.84%)	39% <ø> (-1%)
...tivex/internal/schedulers/TrampolineScheduler.java	94.44% <ø> (-1.39%)	6% <ø> (ø)
...ors/observable/ObservableSampleWithObservable.java	97.59% <ø> (-1.21%)	3% <ø> (ø)
...ternal/operators/completable/CompletableMerge.java	96.42% <ø> (-1.2%)	2% <ø> (ø)
...perators/single/SingleFlatMapIterableFlowable.java	97.5% <ø> (-0.84%)	2% <ø> (ø)
... and 28 more

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[akarnokd]

/cc @davidmoten

[davidmoten]

yep that looks fine. I can do the others.

[davidmoten]

@akarnokd do you want test coverage of the signature changes?

[akarnokd]

Yes, make sure the contravariant consumer now compiles.

[davidmoten]

@jschneider can you add unit tests for this please?

[jschneider]

I will add a test. Yes.

[jschneider]

Added the test

[akarnokd]

Looks like this got a conflict due to changes to RxJavaPlugins by other PRs. Could you rebase this onto the head?

[jschneider]

yep. I am on it

[jschneider]

should be good now.

[akarnokd]

A better type would be Consumer<Object> errorHandler = ...