Polishing

spring-core/src/main/java/org/springframework/util/concurrent/DelegatingCompletableFuture.java

@@ -19,6 +19,8 @@ package org.springframework.util.concurrent;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.Future;
 
+import org.springframework.util.Assert;
+
 /**
  * Extension of {@link CompletableFuture} which allows for cancelling
  * a delegate along with the {@link CompletableFuture} itself.
@@ -30,10 +32,13 @@ class DelegatingCompletableFuture<T> extends CompletableFuture<T> {
 
 	private final Future<T> delegate;
 
+
 	public DelegatingCompletableFuture(Future<T> delegate) {
+		Assert.notNull(delegate, "Delegate must not be null");
 		this.delegate = delegate;
 	}
 
+
 	@Override
 	public boolean cancel(boolean mayInterruptIfRunning) {
 		boolean result = this.delegate.cancel(mayInterruptIfRunning);