2.x: Javadoc space cleanup

[akarnokd]

This PR adds a gradle task to replace the excessive whitespaces generated into the Javadocs between method arguments and after method argument annotations.

This task should run before the javadoc gets packaged up for maven and before it gets pushed back to the gh-pages.

(This was created as a repo branch so that the snapshot pushback is triggered, see the comparison links below.)

Resolves: #6004

Comparison

Multiple parameters before: combineLatest

Multiple parameters after: combineLatest snapshot

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Newline after parameter annotation before: as

Newline after parameter annotation after: as snapshot

[codecov]

Codecov Report

Merging #6005 into 2.x will increase coverage by 0.16%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##                2.x    #6005      +/-   ##
============================================
+ Coverage     98.19%   98.35%   +0.16%     
- Complexity     6061     6065       +4     
============================================
  Files           656      656              
  Lines         44101    44101              
  Branches       6118     6118              
============================================
+ Hits          43304    43376      +72     
+ Misses          245      213      -32     
+ Partials        552      512      -40

Impacted Files	Coverage Δ	Complexity Δ
...rnal/subscriptions/DeferredScalarSubscription.java	98.46% <0%> (-1.54%)	28% <0%> (-1%)
...internal/operators/flowable/FlowableSwitchMap.java	95.28% <0%> (-1.42%)	3% <0%> (ø)
...rnal/operators/flowable/FlowableFlatMapSingle.java	94.56% <0%> (-1.09%)	2% <0%> (ø)
...ernal/operators/flowable/FlowableTimeoutTimed.java	98.37% <0%> (-0.82%)	3% <0%> (ø)
...ernal/operators/flowable/FlowableFromIterable.java	97.32% <0%> (ø)	5% <0%> (ø)	⬇️
...ternal/operators/flowable/FlowableWindowTimed.java	91.62% <0%> (+0.22%)	4% <0%> (ø)	⬇️
...ternal/operators/observable/ObservableFlatMap.java	87.22% <0%> (+0.31%)	3% <0%> (ø)	⬇️
...main/java/io/reactivex/subjects/ReplaySubject.java	98.11% <0%> (+0.41%)	50% <0%> (ø)	⬇️
...x/internal/operators/flowable/FlowableFlatMap.java	90% <0%> (+0.52%)	4% <0%> (ø)	⬇️
...nternal/operators/parallel/ParallelSortedJoin.java	95.62% <0%> (+0.72%)	2% <0%> (ø)	⬇️
... and 20 more

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[vanniktech]

Subjects and Processors are rendering fine?

[akarnokd]

Well, ReplaySubject's multi-parameter methods are a bit misaligned too. Will update list of files.

[akarnokd]

There seems to be a Travis-CI problem; the build is just stuck at the pre-init phase after the network check.