4.x: Flowable API reduction: remaining operators & other related changes

[akarnokd]

Reduce API sufrace by introducing configuration records, plus removing a few overloads regarding TimeUnit followed by a boolean setting. Use the full TimeUnit, Scheduler, xxx overload instead.

Flowable

• remove 2-4 merge overloads
• concatEager
• concatArrayEager
• merge
• zip
• zipArray
• sample + SampleConfig
• throttleLast + SampleConfig
• groupBy
• observeOn
• onBackpressureBuffer + OnBackpressureBufferConfig
• skipLast
• takeLast
• Removed the Action onOverflow parameters since there is the Consumer<T> onDropped

Javadocs

• Cleaned up and described a few items more clearly.

Build

• Gradle 9.6.1 upgraded manually.

Resolves #8173

[github-actions]

🐷 TruffleHog + Entropy Beauty Scan

Average entropy of changed code: 4.78 bits/char
Verdict: ⚠️ Consider review — entropy outside sweet spot

Changed files entropy:

src/jmh/java/io/reactivex/rxjava4/core/FlowableFlatMapCompletableAsyncPerf.java: 5.091
src/jmh/java/io/reactivex/rxjava4/core/FlowableFlatMapCompletableSyncPerf.java: 5.127
src/main/java/io/reactivex/rxjava4/core/Completable.java: 4.835
src/main/java/io/reactivex/rxjava4/core/Flowable.java: 4.783
src/main/java/io/reactivex/rxjava4/core/Maybe.java: 4.842
src/main/java/io/reactivex/rxjava4/core/Observable.java: 4.762
src/main/java/io/reactivex/rxjava4/core/Single.java: 4.831
src/main/java/io/reactivex/rxjava4/core/config/StandardBufferedConfig.java: 4.845
src/main/java/io/reactivex/rxjava4/core/config/StandardConcurrentBufferedConfig.java: 4.857
src/main/module/module-info.java: 4.759
src/test/java/io/reactivex/rxjava4/core/config/StandardConcurrentBufferedConfigTest.java: 4.975
src/test/java/io/reactivex/rxjava4/flowable/FlowableConcatTests.java: 4.822
src/test/java/io/reactivex/rxjava4/flowable/FlowableGroupByTests.java: 4.926
src/test/java/io/reactivex/rxjava4/internal/jdk8/FlowableFlatMapStreamTest.java: 4.561
src/test/java/io/reactivex/rxjava4/internal/operators/flowable/FlowableCombineLatestTest.java: 4.713
src/test/java/io/reactivex/rxjava4/internal/operators/flowable/FlowableConcatDelayErrorTest.java: 4.810
src/test/java/io/reactivex/rxjava4/internal/operators/flowable/FlowableConcatMapEagerTest.java: 4.746
src/test/java/io/reactivex/rxjava4/internal/operators/flowable/FlowableConcatMapSchedulerTest.java: 4.792
src/test/java/io/reactivex/rxjava4/internal/operators/flowable/FlowableConcatMapTest.java: 4.766
src/test/java/io/reactivex/rxjava4/internal/operators/flowable/FlowableConcatTest.java: 4.710

✅ No secrets or suspicious high-entropy strings found.

Mid-4 beauty heuristic in action — powered by our entropy chats! 😊

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.33%. Comparing base (aac2c93) to head (59faba8).
⚠️ Report is 1 commits behind head on 4.x.

Additional details and impacted files

@@             Coverage Diff              @@
##                4.x    #8200      +/-   ##
============================================
- Coverage     98.33%   98.33%   -0.01%     
+ Complexity     6816     6770      -46     
============================================
  Files           775      777       +2     
  Lines         48543    48464      -79     
  Branches       6565     6563       -2     
============================================
- Hits          47737    47656      -81     
  Misses          609      609              
- Partials        197      199       +2     

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