4.x: API reductions: sequenceEqual, switchOnNext, zip

[akarnokd]

Introduce

• ObservableSwitchConfig
• ObservableSequenceEqualConfig
• ObservableZipConfig

Remove

• delayError and/or bufferSize overloads of switchOnNext, sequenceEqual and zip
• xxxDelayError operators.

Correct

• Javadocs of configuration records
• Default values for certain operator configs.
• Copy-paste errors.

Related: #8173

[github-actions]

🐷 TruffleHog + Entropy Beauty Scan

Average entropy of changed code: 4.61 bits/char
Verdict: ✅ Mid-4 beauty detected (thoughtful human code!)

Changed files entropy:

src/main/java/io/reactivex/rxjava4/core/Streamable.java: 4.519
src/main/java/io/reactivex/rxjava4/internal/operators/flowable/FlowableCache.java: 4.357
src/main/java/io/reactivex/rxjava4/internal/operators/flowable/FlowablePublish.java: 4.114
src/main/java/io/reactivex/rxjava4/internal/operators/flowable/FlowablePublishMulticast.java: 3.899
src/main/java/io/reactivex/rxjava4/internal/operators/maybe/MaybeCache.java: 4.428
src/main/java/io/reactivex/rxjava4/internal/operators/single/SingleCache.java: 4.478
src/main/java/io/reactivex/rxjava4/internal/operators/single/SingleOnErrorComplete.java: 4.917
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableEmpty.java: 4.850
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableJust.java: 4.493
src/main/java/io/reactivex/rxjava4/processors/AsyncProcessor.java: 4.728
src/main/java/io/reactivex/rxjava4/processors/BehaviorProcessor.java: 4.596
src/main/java/io/reactivex/rxjava4/processors/MulticastProcessor.java: 4.427
src/main/java/io/reactivex/rxjava4/processors/PublishProcessor.java: 4.708
src/main/java/io/reactivex/rxjava4/processors/ReplayProcessor.java: 4.305
src/main/java/io/reactivex/rxjava4/subjects/AsyncSubject.java: 4.727
src/main/java/io/reactivex/rxjava4/subjects/BehaviorSubject.java: 4.601
src/main/java/io/reactivex/rxjava4/subjects/MaybeSubject.java: 4.754
src/main/java/io/reactivex/rxjava4/subjects/PublishSubject.java: 4.712
src/main/java/io/reactivex/rxjava4/subjects/ReplaySubject.java: 4.370
src/main/java/io/reactivex/rxjava4/subjects/SingleSubject.java: 4.731

✅ 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 98.35%. Comparing base (d8e5803) to head (58f7c73).

Additional details and impacted files

@@            Coverage Diff            @@
##                4.x    #8190   +/-   ##
=========================================
  Coverage     98.35%   98.35%           
- Complexity     6930     6936    +6     
=========================================
  Files           785      788    +3     
  Lines         48754    48777   +23     
  Branches       6594     6594           
=========================================
+ Hits          47950    47973   +23     
- Misses          609      610    +1     
+ Partials        195      194    -1     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.