From 25561784228a60c125a237933f5064ecfde1a96e Mon Sep 17 00:00:00 2001
From: Violeta Georgieva <vgeorgieva@pivotal.io>
Date: Tue, 28 Mar 2017 14:08:13 +0300
Subject: [PATCH] Ensure NPE will not be thrown when cancelling a subscription

Issue: SPR-15393
---
 .../server/reactive/AbstractListenerWriteFlushProcessor.java  | 4 +++-
 .../http/server/reactive/AbstractListenerWriteProcessor.java  | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteFlushProcessor.java b/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteFlushProcessor.java
index 42797152a6..00de5e141e 100644
--- a/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteFlushProcessor.java
+++ b/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteFlushProcessor.java
@@ -98,7 +98,9 @@ public abstract class AbstractListenerWriteFlushProcessor<T> implements Processo
 	 * Listeners can call this method to cancel further writing.
 	 */
 	protected void cancel() {
-		this.subscription.cancel();
+		if (this.subscription != null) {
+			this.subscription.cancel();
+		}
 	}
 
 
diff --git a/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteProcessor.java b/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteProcessor.java
index eb1bbccd8b..45b24f1566 100644
--- a/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteProcessor.java
+++ b/spring-web/src/main/java/org/springframework/http/server/reactive/AbstractListenerWriteProcessor.java
@@ -111,7 +111,9 @@ public abstract class AbstractListenerWriteProcessor<T> implements Processor<T,
 	 * Listeners can call this method to cancel further writing.
 	 */
 	public void cancel() {
-		this.subscription.cancel();
+		if (this.subscription != null) {
+			this.subscription.cancel();
+		}
 	}