4.x: What's different in 4.0 documentation, start

[akarnokd]

With some attitude nonetheless.

Release is November 30, 2026 so about time the documentation starts listing and explaining the changes.

Once done, it will be also put into the wiki.

[github-actions]

🐷 TruffleHog + Entropy Beauty Scan

Average entropy of changed code: 4.632 bits/char
Verdict: ✅ Mid-4 beauty detected (thoughtful human code!)

Changed files entropy:

src/main/java/io/reactivex/rxjava4/core/CompletionStageDisposable.java: 4.613
src/main/java/io/reactivex/rxjava4/core/StreamProcessor.java: 4.842
src/main/java/io/reactivex/rxjava4/core/StreamSink.java: 4.736
src/main/java/io/reactivex/rxjava4/core/Streamable.java: 4.653
src/main/java/io/reactivex/rxjava4/core/Streamer.java: 4.688
src/main/java/io/reactivex/rxjava4/exceptions/Exceptions.java: 4.732
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamSinkLambda.java: 4.890
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamSinkWithCancellation.java: 4.923
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableForEach.java: 4.149
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableGroupBy.java: 4.335
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableHelper.java: 4.411
src/main/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableTimer.java: 4.544
src/main/java/io/reactivex/rxjava4/internal/util/ExceptionHelper.java: 4.501
src/main/java/io/reactivex/rxjava4/internal/virtual/FlowableVirtualCreateExecutor.java: 4.454
src/main/java/io/reactivex/rxjava4/internal/virtual/FlowableVirtualTransformExecutor.java: 4.150
src/main/java/io/reactivex/rxjava4/processors/DispatchStreamProcessor.java: 4.574
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/DispatchStreamProcessorTest.java: 4.639
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableBaseTest.java: 4.786
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableDoOnErrorTest.java: 4.835
src/test/java/io/reactivex/rxjava4/internal/operators/streamable/StreamableDoOnNextTest.java: 4.909

✅ 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 98.69%. Comparing base (c027d00) to head (a97e8b2).

Additional details and impacted files

@@             Coverage Diff              @@
##                4.x    #8219      +/-   ##
============================================
- Coverage     98.69%   98.69%   -0.01%     
+ Complexity     7096     7094       -2     
============================================
  Files           812      812              
  Lines         49935    49935              
  Branches       6755     6755              
============================================
- Hits          49285    49281       -4     
- Misses          454      458       +4     
  Partials        196      196              

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