Support for null in mapAsync and fromCompletionStage #25475

akka-docs/src/main/paradox/stream/operators/Source-or-Flow/mapAsync.md

@@ -18,6 +18,7 @@ Pass incoming elements to a function that return a @scala[`Future`] @java[`Compl
 downstream. Up to `n` elements can be processed concurrently, but regardless of their completion time the incoming
 order will be kept when results complete. For use cases where order does not matter `mapAsyncUnordered` can be used.
 
+If a @scala[`Future`] @java[`CompletionStage`] completes with `null`, element is not passed downstream.
 If a @scala[`Future`] @java[`CompletionStage`] fails, the stream also fails (unless a different supervision strategy is applied)
 
 

akka-docs/src/main/paradox/stream/operators/Source-or-Flow/mapAsyncUnordered.md

@@ -17,6 +17,7 @@ Like `mapAsync` but @scala[`Future`] @java[`CompletionStage`] results are passed
 Like `mapAsync` but @scala[`Future`] @java[`CompletionStage`] results are passed downstream as they arrive regardless of the order of the elements
 that triggered them.
 
+If a @scala[`Future`] @java[`CompletionStage`] completes with `null`, element is not passed downstream.
 If a @scala[`Future`] @java[`CompletionStage`] fails, the stream also fails (unless a different supervision strategy is applied)
 
 

akka-docs/src/main/paradox/stream/operators/Source/fromCompletionStage.md

@@ -15,7 +15,8 @@ Send the single value of the `CompletionStage` when it completes and there is de
 ## Description
 
 Send the single value of the `CompletionStage` when it completes and there is demand.
-If the future fails the stream is failed with that exception.
+If the `CompletionStage` completes with `null` stage is completed without emitting a value.
+If the `CompletionStage` fails the stream is failed with that exception.
 
 
 @@@div { .callout }