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Address NullAway warnings and refine StepVerifier nullability#4126

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chemicL merged 21 commits intomainfrom
remaining-nullability-handling
Oct 31, 2025
Merged

Address NullAway warnings and refine StepVerifier nullability#4126
chemicL merged 21 commits intomainfrom
remaining-nullability-handling

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@chemicL chemicL commented Oct 31, 2025

This PR addresses the remaining NullAway warnings left after #4091.

It also contains public API refinenements around StepVerifier and TestPublisher from reactor-test to allow verifying non-compliant Publishers against null values.

Follow-up on #878

chemicL added 21 commits October 22, 2025 20:37
@chemicL
Add implementation suppressions and nullability annotations
d4f45dc 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
Adjust ParallelMergeReduce nullability
bd3a736 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
Adjust FluxGroupBy nullability
0ace8c4 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
Adjust FluxSwitchOnFirst nullability
9d409ef 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
Adjust more operators nullability
8fdd8a4 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
More nullability refinements
f3e1414 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
License
d02ebdb 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
Update InnerProducer#actual and FluxWindowPredicate that can have nul…
d7b1d1c 
…l actual

Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
More nullability refinements
6b3ff8e 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
Mass replace Throwable error fields with nullable variant
1a6f0dd 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
Mass replace Throwable error fields with nullable variant
70383e5 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
More nullability refinements
7e6c862 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
More nullability refinements
29b4698 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
More nullability refinements
7b1e692 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
More nullability refinements
c30cf6f 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
Refine actual() internal nullability treatment and one assertion
3544a97 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
More nullability refinements
07f75d1 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
More nullability refinements
5fa0709 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
More nullability refinements
e23aa2a 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
More nullability refinements
c7be2e5 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL
Refine StepVerifier nullability in public API to allow nulls
3ce61fe 
Signed-off-by: Dariusz Jędrzejczyk <dariusz.jedrzejczyk@broadcom.com>
@chemicL chemicL added this to the 3.8.0 milestone Oct 31, 2025
@chemicL chemicL requested a review from a team as a code owner October 31, 2025 13:23
@chemicL chemicL added type/enhancement A general enhancement warn/api-change Breaking change with compilation errors labels Oct 31, 2025
github-advanced-security[bot]
github-advanced-security bot found potential problems Oct 31, 2025
View reviewed changes
reactor-core/src/main/java/reactor/core/publisher/FluxBufferWhen.java
return;
}
queue.offer(buffers.remove(idx));
queue.offer(bufs.remove(idx));

Check notice

Code scanning / CodeQL

Ignored error status of call Note

Method close ignores exceptional return value of Queue.offer.
reactor-core/src/main/java/reactor/core/publisher/FluxReplay.java
break;
}

assert next != null && next.value != null : "next and next.value must not be null";

Check warning

Code scanning / CodeQL

Useless null check Warning

This check is useless.
next
Loading
cannot be null at this check, since it is guarded by
... == ...
Loading
.

Copilot Autofix

AI 4 months ago

To fix the problem, the unnecessary redundancy in the assertion at line 241 should be eliminated. Specifically, the check for next != null is not needed as the control flow guarantees next is never null at this point. The best way to fix this without changing existing functionality is:

  • In reactor-core/src/main/java/reactor/core/publisher/FluxReplay.java at line 241, change assert next != null && next.value != null : "next and next.value must not be null"; to assert next.value != null : "next.value must not be null";
  • No additional imports or method changes are required.
Suggested changeset 1
reactor-core/src/main/java/reactor/core/publisher/FluxReplay.java

Autofix patch

Autofix patch
Run the following command in your local git repository to apply this patch
cat << 'EOF' | git apply
diff --git a/reactor-core/src/main/java/reactor/core/publisher/FluxReplay.java b/reactor-core/src/main/java/reactor/core/publisher/FluxReplay.java
--- a/reactor-core/src/main/java/reactor/core/publisher/FluxReplay.java
+++ b/reactor-core/src/main/java/reactor/core/publisher/FluxReplay.java
@@ -238,7 +238,7 @@
 						break;
 					}
 
-					assert next != null && next.value != null : "next and next.value must not be null";
+					assert next.value != null : "next.value must not be null";
 					a.onNext(next.value);
 
 					e++;
EOF
@@ -238,7 +238,7 @@
break;
}

assert next != null && next.value != null : "next and next.value must not be null";
assert next.value != null : "next.value must not be null";
a.onNext(next.value);

e++;
Copilot is powered by AI and may make mistakes. Always verify output.
reactor-core/src/main/java/reactor/core/publisher/FluxReplay.java
break;
}

assert next != null && next.value != null : "next and next.value must not be null";

Check warning

Code scanning / CodeQL

Useless null check Warning

This check is useless.
next
Loading
cannot be null at this check, since it is guarded by
... == ...
Loading
.

Copilot Autofix

AI 4 months ago

To fix the problem, remove the useless check for next != null in the assertion at line 882. Since the empty case was already handled, the assertion only needs to check that next.value != null. No new methods, imports, or definitions are needed. Only alter the relevant assertion in reactor-core/src/main/java/reactor/core/publisher/FluxReplay.java.

Suggested changeset 1
reactor-core/src/main/java/reactor/core/publisher/FluxReplay.java

Autofix patch

Autofix patch
Run the following command in your local git repository to apply this patch
cat << 'EOF' | git apply
diff --git a/reactor-core/src/main/java/reactor/core/publisher/FluxReplay.java b/reactor-core/src/main/java/reactor/core/publisher/FluxReplay.java
--- a/reactor-core/src/main/java/reactor/core/publisher/FluxReplay.java
+++ b/reactor-core/src/main/java/reactor/core/publisher/FluxReplay.java
@@ -879,7 +879,7 @@
 						break;
 					}
 
-					assert next != null && next.value != null : "next and next.value must not be null";
+					assert next.value != null : "next.value must not be null";
 					a.onNext(next.value);
 
 					e++;
EOF
@@ -879,7 +879,7 @@
break;
}

assert next != null && next.value != null : "next and next.value must not be null";
assert next.value != null : "next.value must not be null";
a.onNext(next.value);

e++;
Copilot is powered by AI and may make mistakes. Always verify output.
reactor-core/src/main/java/reactor/core/publisher/FluxSwitchMapNoPrefetch.java
}

// NullAway issue?
assert si != null : "si can not be null here";

Check warning

Code scanning / CodeQL

Useless null check Warning

This check is useless.
si
Loading
cannot be null at this check, since it is guarded by
... != ...
Loading
.

Copilot Autofix

AI 4 months ago

The best fix is to remove the redundant assertion statement on line 169: assert si != null : "si can not be null here";. This will clean up the code, improve readability, and avoid confusion or misleading logic. All other functionality is preserved. No other definitions or imports are needed.

Make this change only in reactor-core/src/main/java/reactor/core/publisher/FluxSwitchMapNoPrefetch.java.

Suggested changeset 1
reactor-core/src/main/java/reactor/core/publisher/FluxSwitchMapNoPrefetch.java

Autofix patch

Autofix patch
Run the following command in your local git repository to apply this patch
cat << 'EOF' | git apply
diff --git a/reactor-core/src/main/java/reactor/core/publisher/FluxSwitchMapNoPrefetch.java b/reactor-core/src/main/java/reactor/core/publisher/FluxSwitchMapNoPrefetch.java
--- a/reactor-core/src/main/java/reactor/core/publisher/FluxSwitchMapNoPrefetch.java
+++ b/reactor-core/src/main/java/reactor/core/publisher/FluxSwitchMapNoPrefetch.java
@@ -166,7 +166,6 @@
 			}
 
 			// NullAway issue?
-			assert si != null : "si can not be null here";
 			final int nextIndex = si.index + 1;
 			final SwitchMapInner<T, R> nsi = new SwitchMapInner<>(this, this.actual, nextIndex, this.logger);
 
EOF
@@ -166,7 +166,6 @@
}

// NullAway issue?
assert si != null : "si can not be null here";
final int nextIndex = si.index + 1;
final SwitchMapInner<T, R> nsi = new SwitchMapInner<>(this, this.actual, nextIndex, this.logger);

Copilot is powered by AI and may make mistakes. Always verify output.
reactor-core/src/main/java/reactor/core/publisher/SinkManyEmitterProcessor.java
FluxPublish.PubSubInner<T>[] a = subscribers;

if (a != EMPTY && !empty) {
assert q != null : "q can not be null when !empty";

Check warning

Code scanning / CodeQL

Useless null check Warning

This check is useless.
q
Loading
cannot be null at this check, since it is guarded by
... == ...
Loading
.

Copilot Autofix

AI 4 months ago

To fix the problem, remove the unnecessary assertion assert q != null : "q can not be null when !empty"; on line 410. This will clean up the code by eliminating misleading checks, reducing clutter, and making intent clearer, as the previous guard ensures this case is impossible.

No imports or other definitions are needed for this edit. Only the code in the vicinity of line 410, in the drain() method of reactor-core/src/main/java/reactor/core/publisher/SinkManyEmitterProcessor.java, needs to be changed.

Suggested changeset 1
reactor-core/src/main/java/reactor/core/publisher/SinkManyEmitterProcessor.java

Autofix patch

Autofix patch
Run the following command in your local git repository to apply this patch
cat << 'EOF' | git apply
diff --git a/reactor-core/src/main/java/reactor/core/publisher/SinkManyEmitterProcessor.java b/reactor-core/src/main/java/reactor/core/publisher/SinkManyEmitterProcessor.java
--- a/reactor-core/src/main/java/reactor/core/publisher/SinkManyEmitterProcessor.java
+++ b/reactor-core/src/main/java/reactor/core/publisher/SinkManyEmitterProcessor.java
@@ -407,7 +407,6 @@
 			FluxPublish.PubSubInner<T>[] a = subscribers;
 
 			if (a != EMPTY && !empty) {
-				assert q != null : "q can not be null when !empty";
 				long maxRequested = Long.MAX_VALUE;
 
 				int len = a.length;
EOF
@@ -407,7 +407,6 @@
FluxPublish.PubSubInner<T>[] a = subscribers;

if (a != EMPTY && !empty) {
assert q != null : "q can not be null when !empty";
long maxRequested = Long.MAX_VALUE;

int len = a.length;
Copilot is powered by AI and may make mistakes. Always verify output.
@chemicL chemicL merged commit 03521d9 into main Oct 31, 2025
11 checks passed
@chemicL chemicL deleted the remaining-nullability-handling branch October 31, 2025 17:03
@chemicL chemicL removed the warn/api-change Breaking change with compilation errors label Oct 31, 2025
@chemicL chemicL mentioned this pull request Oct 31, 2025
Merged
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