Restore if (message != null) { in the IntegrationReactiveUtils

Author: artembilan

spring-integration-core/src/main/java/org/springframework/integration/util/IntegrationReactiveUtils.java

@@ -133,7 +133,9 @@ public static <T> Flux<Message<T>> messageSourceToFlux(MessageSource<T> messageS
 				<Message<T>>create(monoSink ->
 				monoSink.onRequest(value -> monoSink.success(messageSource.receive())))
 				.doOnSuccess((message) -> {
-					AckUtils.autoAck(StaticMessageHeaderAccessor.getAcknowledgmentCallback(message));
+					if (message != null) {
+						AckUtils.autoAck(StaticMessageHeaderAccessor.getAcknowledgmentCallback(message));
+					}
 				})
 				.doOnError(MessagingException.class,
 						(ex) -> {